TabbedPane: support alignment of tab area (leading, trailing, center or fill)

CHANGELOG.md

@@ -21,6 +21,9 @@ FlatLaf Change Log
 - TabbedPane: Support closable tabs. (PR #193; issues #31 and #40)
 - TabbedPane: Support minimum or maximum tab widths. (set client property
   `JTabbedPane.minimumTabWidth` or `JTabbedPane.maximumTabWidth` to an integer)
+- TabbedPane: Support alignment of tab area. (set client property
+  `JTabbedPane.tabAreaAlignment` to `"leading"`, `"trailing"`, `"center"` or
+  `"fill"`)
 - Support painting separator line between window title and content (use UI value
   `TitlePane.borderColor`). (issue #184)
 - Extras: `FlatSVGIcon` now allows specifying icon width and height in

flatlaf-core/src/main/java/com/formdev/flatlaf/FlatClientProperties.java

@@ -371,6 +371,45 @@ public interface FlatClientProperties
 	 */
 	String TABBED_PANE_HIDDEN_TABS_NAVIGATION_ARROW_BUTTONS = "arrowButtons";
 
+	/**
+	 * Specifies the alignment of the tab area.
+	 * <p>
+	 * <strong>Component</strong> {@link javax.swing.JTabbedPane}<br>
+	 * <strong>Value type</strong> {@link java.lang.String}
+	 * <strong>Allowed Values</strong> {@link #TABBED_PANE_TAB_AREA_ALIGN_LEADING} (default),
+	 * {@link #TABBED_PANE_TAB_AREA_ALIGN_TRAILING}, {@link #TABBED_PANE_TAB_AREA_ALIGN_CENTER}
+	 * or {@link #TABBED_PANE_TAB_AREA_ALIGN_FILL}
+	 */
+	String TABBED_PANE_TAB_AREA_ALIGNMENT = "JTabbedPane.tabAreaAlignment";
+
+	/**
+	 * Align the tab area to the leading edge.
+	 *
+	 * @see #TABBED_PANE_TAB_AREA_ALIGNMENT
+	 */
+	String TABBED_PANE_TAB_AREA_ALIGN_LEADING = "leading";
+
+	/**
+	 * Align the tab area to the trailing edge.
+	 *
+	 * @see #TABBED_PANE_TAB_AREA_ALIGNMENT
+	 */
+	String TABBED_PANE_TAB_AREA_ALIGN_TRAILING = "trailing";
+
+	/**
+	 * Align the tab area to center.
+	 *
+	 * @see #TABBED_PANE_TAB_AREA_ALIGNMENT
+	 */
+	String TABBED_PANE_TAB_AREA_ALIGN_CENTER = "center";
+
+	/**
+	 * Stretch tabs to fill all available space.
+	 *
+	 * @see #TABBED_PANE_TAB_AREA_ALIGNMENT
+	 */
+	String TABBED_PANE_TAB_AREA_ALIGN_FILL = "fill";
+
 	/**
 	 * Specifies a component that will be placed at the leading edge of the tabs area.
 	 * <p>

flatlaf-core/src/main/java/com/formdev/flatlaf/ui/FlatTabbedPaneUI.java

@@ -127,6 +127,7 @@ import com.formdev.flatlaf.util.UIScale;
  * @uiDefault TabbedPane.tabSeparatorsFullHeight		boolean
  * @uiDefault TabbedPane.hasFullBorder					boolean
  * @uiDefault TabbedPane.hiddenTabsNavigation			String	moreTabsButton (default) or arrowButtons
+ * @uiDefault TabbedPane.tabAreaAlignment				String	leading (default), center, trailing or fill
  * @uiDefault ScrollPane.smoothScrolling				boolean
  * @uiDefault TabbedPane.closeIcon						Icon
  *
@@ -141,6 +142,12 @@ public class FlatTabbedPaneUI
 	protected static final int MORE_TABS_BUTTON = 0;
 	protected static final int ARROW_BUTTONS = 1;
 
+	// tab area alignment
+	protected static final int ALIGN_LEADING = 0;
+	protected static final int ALIGN_TRAILING = 1;
+	protected static final int ALIGN_CENTER = 2;
+	protected static final int ALIGN_FILL = 3;
+
 	private static Set<KeyStroke> focusForwardTraversalKeys;
 	private static Set<KeyStroke> focusBackwardTraversalKeys;
 
@@ -166,6 +173,7 @@ public class FlatTabbedPaneUI
 	protected boolean tabsOpaque = true;
 
 	private String hiddenTabsNavigationStr;
+	private String tabAreaAlignmentStr;
 	protected Icon closeIcon;
 
 	protected String moreTabsButtonToolTipText;
@@ -232,6 +240,7 @@ public class FlatTabbedPaneUI
 		hasFullBorder = UIManager.getBoolean( "TabbedPane.hasFullBorder" );
 		tabsOpaque = UIManager.getBoolean( "TabbedPane.tabsOpaque" );
 		hiddenTabsNavigationStr = UIManager.getString( "TabbedPane.hiddenTabsNavigation" );
+		tabAreaAlignmentStr = UIManager.getString( "TabbedPane.tabAreaAlignment" );
 		closeIcon = UIManager.getIcon( "TabbedPane.closeIcon" );
 
 		Locale l = tabPane.getLocale();
@@ -548,24 +557,6 @@ public class FlatTabbedPaneUI
 		return Math.max( tabHeight, super.calculateTabHeight( tabPlacement, tabIndex, fontHeight ) - 2 /* was added by superclass */ );
 	}
 
-	protected int calculateMaxExtrasWidth() {
-		int width = 0;
-		if( leadingComponent != null )
-			width = Math.max( width, leadingComponent.getPreferredSize().width );
-		if( trailingComponent != null )
-			width = Math.max( width, trailingComponent.getPreferredSize().width );
-		return width;
-	}
-
-	protected int calculateMaxExtrasHeight() {
-		int height = 0;
-		if( leadingComponent != null )
-			height = Math.max( height, leadingComponent.getPreferredSize().height );
-		if( trailingComponent != null )
-			height = Math.max( height, trailingComponent.getPreferredSize().height );
-		return height;
-	}
-
 	@Override
 	protected Insets getTabInsets( int tabPlacement, int tabIndex ) {
 		Object value = getTabClientProperty( tabIndex, TABBED_PANE_TAB_INSETS );
@@ -579,8 +570,7 @@ public class FlatTabbedPaneUI
 		return new Insets( 0, 0, 0, 0 );
 	}
 
-	@Override
+	protected Insets getRealTabAreaInsets( int tabPlacement ) {
-	protected Insets getTabAreaInsets( int tabPlacement ) {
 		Insets currentTabAreaInsets = super.getTabAreaInsets( tabPlacement );
 		Insets insets = (Insets) currentTabAreaInsets.clone();
 
@@ -594,21 +584,21 @@ public class FlatTabbedPaneUI
 		// scale insets (before adding leading/trailing component sizes)
 		insets = scale( insets );
 
+		return insets;
+	}
+
+	@Override
+	protected Insets getTabAreaInsets( int tabPlacement ) {
+		Insets insets = getRealTabAreaInsets( tabPlacement );
+
 		// increase insets for wrap layout if using leading/trailing components
 		if( tabPane.getTabLayoutPolicy() == JTabbedPane.WRAP_TAB_LAYOUT ) {
-			if( leadingComponent != null ) {
+			if( isHorizontalTabPlacement() ) {
-				Dimension leadingSize = leadingComponent.getPreferredSize();
+				insets.left += getLeadingPreferredWidth();
-				if( isHorizontalTabPlacement() )
+				insets.right += getTrailingPreferredWidth();
-					insets.left += leadingSize.width;
+			} else {
-				else
+				insets.top += getLeadingPreferredHeight();
-					insets.top += leadingSize.height;
+				insets.bottom += getTrailingPreferredHeight();
-			}
-			if( trailingComponent != null ) {
-				Dimension trailingSize = trailingComponent.getPreferredSize();
-				if( isHorizontalTabPlacement() )
-					insets.right += trailingSize.width;
-				else
-					insets.bottom += trailingSize.height;
 			}
 		}
 
@@ -1101,10 +1091,17 @@ public class FlatTabbedPaneUI
 	}
 
 	protected int getHiddenTabsNavigation() {
-		String hiddenTabsNavigationStr = (String) tabPane.getClientProperty( TABBED_PANE_HIDDEN_TABS_NAVIGATION );
+		String str = (String) tabPane.getClientProperty( TABBED_PANE_HIDDEN_TABS_NAVIGATION );
-		if( hiddenTabsNavigationStr == null )
+		if( str == null )
-			hiddenTabsNavigationStr = this.hiddenTabsNavigationStr;
+			str = hiddenTabsNavigationStr;
-		return parseHiddenTabsNavigation( hiddenTabsNavigationStr );
+		return parseHiddenTabsNavigation( str );
+	}
+
+	protected int getTabAreaAlignment() {
+		String str = (String) tabPane.getClientProperty( TABBED_PANE_TAB_AREA_ALIGNMENT );
+		if( str == null )
+			str = tabAreaAlignmentStr;
+		return parseTabAreaAlignment( str );
 	}
 
 	protected static int parseHiddenTabsNavigation( String str ) {
@@ -1113,8 +1110,21 @@ public class FlatTabbedPaneUI
 
 		switch( str ) {
 			default:
-			case "moreTabsButton":	return MORE_TABS_BUTTON;
+			case TABBED_PANE_HIDDEN_TABS_NAVIGATION_MORE_TABS_BUTTON:	return MORE_TABS_BUTTON;
-			case "arrowButtons":	return ARROW_BUTTONS;
+			case TABBED_PANE_HIDDEN_TABS_NAVIGATION_ARROW_BUTTONS:		return ARROW_BUTTONS;
+		}
+	}
+
+	protected static int parseTabAreaAlignment( String str ) {
+		if( str == null )
+			return ALIGN_LEADING;
+
+		switch( str ) {
+			default:
+			case TABBED_PANE_TAB_AREA_ALIGN_LEADING:	return ALIGN_LEADING;
+			case TABBED_PANE_TAB_AREA_ALIGN_TRAILING:	return ALIGN_TRAILING;
+			case TABBED_PANE_TAB_AREA_ALIGN_CENTER:		return ALIGN_CENTER;
+			case TABBED_PANE_TAB_AREA_ALIGN_FILL:		return ALIGN_FILL;
 		}
 	}
 
@@ -1149,6 +1159,22 @@ public class FlatTabbedPaneUI
 		((JComponent)tabViewport.getView()).scrollRectToVisible( (Rectangle) rects[selectedIndex].clone() );
 	}
 
+	private int getLeadingPreferredWidth() {
+		return (leadingComponent != null) ? leadingComponent.getPreferredSize().width : 0;
+	}
+
+	private int getLeadingPreferredHeight() {
+		return (leadingComponent != null) ? leadingComponent.getPreferredSize().height : 0;
+	}
+
+	private int getTrailingPreferredWidth() {
+		return (trailingComponent != null) ? trailingComponent.getPreferredSize().width : 0;
+	}
+
+	private int getTrailingPreferredHeight() {
+		return (trailingComponent != null) ? trailingComponent.getPreferredSize().height : 0;
+	}
+
 	private void shiftTabs( int sx, int sy ) {
 		if( sx == 0 && sy == 0 )
 			return;
@@ -1165,6 +1191,64 @@ public class FlatTabbedPaneUI
 		}
 	}
 
+	private void stretchTabsWidth( int sw, boolean leftToRight ) {
+		int rsw = sw / rects.length;
+		int x = rects[0].x - (leftToRight ? 0 : rsw);
+		for( int i = 0; i < rects.length; i++ ) {
+			// fix tab component location
+			Component c = tabPane.getTabComponentAt( i );
+			if( c != null )
+				c.setLocation( x + (c.getX() - rects[i].x) + (rsw / 2), c.getY() );
+
+			// fix x location and width in rects
+			rects[i].x = x;
+			rects[i].width += rsw;
+
+			if( leftToRight )
+				x += rects[i].width;
+			else if( i + 1 < rects.length )
+				x = rects[i].x - rects[i+1].width - rsw;
+		}
+
+		// fix width of last tab
+		int diff = sw - (rsw * rects.length);
+		rects[rects.length-1].width += diff;
+		if( !leftToRight )
+			rects[rects.length-1].x -= diff;
+	}
+
+	private void stretchTabsHeight( int sh ) {
+		int rsh = sh / rects.length;
+		int y = rects[0].y;
+		for( int i = 0; i < rects.length; i++ ) {
+			// fix tab component location
+			Component c = tabPane.getTabComponentAt( i );
+			if( c != null )
+				c.setLocation( c.getX(), y + (c.getY() - rects[i].y) + (rsh / 2) );
+
+			// fix y location and height in rects
+			rects[i].y = y;
+			rects[i].height += rsh;
+
+			y += rects[i].height;
+		}
+
+		// fix height of last tab
+		rects[rects.length-1].height += (sh - (rsh * rects.length));
+	}
+
+	private int rectsTotalWidth( boolean leftToRight ) {
+		int last = rects.length - 1;
+		return leftToRight
+			? (rects[last].x + rects[last].width) - rects[0].x
+			: (rects[0].x + rects[0].width) - rects[last].x;
+	}
+
+	private int rectsTotalHeight() {
+		int last = rects.length - 1;
+		return (rects[last].y + rects[last].height) - rects[0].y;
+	}
+
 	//---- class TabCloseButton -----------------------------------------------
 
 	private class TabCloseButton
@@ -1796,6 +1880,7 @@ public class FlatTabbedPaneUI
 				case TABBED_PANE_TAB_HEIGHT:
 				case TABBED_PANE_TAB_INSETS:
 				case TABBED_PANE_HIDDEN_TABS_NAVIGATION:
+				case TABBED_PANE_TAB_AREA_ALIGNMENT:
 				case TABBED_PANE_TAB_CLOSABLE:
 					tabPane.revalidate();
 					tabPane.repaint();
@@ -1883,19 +1968,22 @@ public class FlatTabbedPaneUI
 			Rectangle bounds = tabPane.getBounds();
 			Insets insets = tabPane.getInsets();
 			int tabPlacement = tabPane.getTabPlacement();
-			Insets tabAreaInsets = getTabAreaInsets( tabPlacement );
+			int tabAreaAlignment = getTabAreaAlignment();
+			Insets tabAreaInsets = getRealTabAreaInsets( tabPlacement );
 			boolean leftToRight = isLeftToRight();
 
 			// layout leading and trailing components in tab area
 			if( tabPlacement == TOP || tabPlacement == BOTTOM ) {
 				// fix x-locations of tabs in right-to-left component orientation
 				if( !leftToRight )
-					shiftTabs( insets.left + tabAreaInsets.right, 0 );
+					shiftTabs( insets.left + tabAreaInsets.right + getTrailingPreferredWidth(), 0 );
 
 				// tab area height (maxTabHeight is zero if tab count is zero)
 				int tabAreaHeight = (maxTabHeight > 0)
 					? maxTabHeight
-					: Math.max( calculateMaxExtrasHeight(), scale( clientPropertyInt( tabPane, TABBED_PANE_TAB_HEIGHT, tabHeight ) ) );
+					: Math.max(
+						Math.max( getLeadingPreferredHeight(), getTrailingPreferredHeight() ),
+						scale( clientPropertyInt( tabPane, TABBED_PANE_TAB_HEIGHT, tabHeight ) ) );
 
 				// tab area bounds
 				int tx = insets.left;
@@ -1905,38 +1993,56 @@ public class FlatTabbedPaneUI
 				int tw = bounds.width - insets.left - insets.right;
 				int th = tabAreaHeight;
 
+				int leadingWidth = getLeadingPreferredWidth();
+				int trailingWidth = getTrailingPreferredWidth();
+
+				// apply tab area alignment
+				if( runCount == 1 && rects.length > 0 ) {
+					int availWidth = tw - leadingWidth - trailingWidth - tabAreaInsets.left - tabAreaInsets.right;
+					int totalTabWidth = rectsTotalWidth( leftToRight );
+					int diff = availWidth - totalTabWidth;
+
+					switch( tabAreaAlignment ) {
+						case ALIGN_LEADING:
+							trailingWidth += diff;
+							break;
+
+						case ALIGN_TRAILING:
+							shiftTabs( leftToRight ? diff : -diff, 0 );
+							leadingWidth += diff;
+							break;
+
+						case ALIGN_CENTER:
+							shiftTabs( (leftToRight ? diff : -diff) / 2, 0 );
+							leadingWidth += diff / 2;
+							trailingWidth += diff - (diff / 2);
+							break;
+
+						case ALIGN_FILL:
+							stretchTabsWidth( diff, leftToRight );
+							break;
+					}
+				} else if( rects.length == 0 )
+					trailingWidth = tw - leadingWidth;
+
 				// layout left component
 				Container leftComponent = leftToRight ? leadingComponent : trailingComponent;
 				if( leftComponent != null ) {
-					// trailing component fills all available horizontal space
+					int leftWidth = leftToRight ? leadingWidth : trailingWidth;
-					int leftWidth = leftToRight
-						? leftComponent.getPreferredSize().width
-						: (rects.length > 0
-							? rects[rects.length-1].x - tx
-								- (tabAreaInsets.right - trailingComponent.getPreferredSize().width)
-							: tw - (leadingComponent != null ? leadingComponent.getPreferredSize().width : 0));
 					leftComponent.setBounds( tx, ty, leftWidth, th );
-
-					// reduce tab area bounds
-					tx += leftWidth;
-					tw -= leftWidth;
 				}
 
 				// layout right component
 				Container rightComponent = leftToRight ? trailingComponent : leadingComponent;
 				if( rightComponent != null ) {
-					// trailing component fills all available horizontal space
+					int rightWidth = leftToRight ? trailingWidth : leadingWidth;
-					int rightWidth = !leftToRight
-						? rightComponent.getPreferredSize().width
-						: (rects.length > 0
-							? tx + tw - (rects[rects.length-1].x + rects[rects.length-1].width)
-								- (tabAreaInsets.right - trailingComponent.getPreferredSize().width)
-							: tw);
 					rightComponent.setBounds( tx + tw - rightWidth, ty, rightWidth, th );
 				}
 			} else { // LEFT and RIGHT tab placement
 				// tab area width (maxTabWidth is zero if tab count is zero)
-				int tabAreaWidth = (maxTabWidth > 0) ? maxTabWidth : calculateMaxExtrasWidth();
+				int tabAreaWidth = (maxTabWidth > 0)
+					? maxTabWidth
+					: Math.max( getLeadingPreferredWidth(), getTrailingPreferredWidth() );
 
 				// tab area bounds
 				int tx = (tabPlacement == LEFT)
@@ -1946,25 +2052,45 @@ public class FlatTabbedPaneUI
 				int tw = tabAreaWidth;
 				int th = bounds.height - insets.top - insets.bottom;
 
+				int topHeight = getLeadingPreferredHeight();
+				int bottomHeight = getTrailingPreferredHeight();
+
+				// apply tab area alignment
+				if( runCount == 1 && rects.length > 0 ) {
+					int availHeight = th - topHeight - bottomHeight - tabAreaInsets.top - tabAreaInsets.bottom;
+					int totalTabHeight = rectsTotalHeight();
+					int diff = availHeight - totalTabHeight;
+
+					switch( tabAreaAlignment ) {
+						case ALIGN_LEADING:
+							bottomHeight += diff;
+							break;
+
+						case ALIGN_TRAILING:
+							shiftTabs( 0, diff );
+							topHeight += diff;
+							break;
+
+						case ALIGN_CENTER:
+							shiftTabs( 0, (diff) / 2 );
+							topHeight += diff / 2;
+							bottomHeight += diff - (diff / 2);
+							break;
+
+						case ALIGN_FILL:
+							stretchTabsHeight( diff );
+							break;
+					}
+				} else if( rects.length == 0 )
+					bottomHeight = th - topHeight;
+
 				// layout top component
-				if( leadingComponent != null ) {
+				if( leadingComponent != null )
-					int topHeight = leadingComponent.getPreferredSize().height;
 					leadingComponent.setBounds( tx, ty, tw, topHeight );
 
-					// reduce tab area bounds
-					ty += topHeight;
-					th -= topHeight;
-				}
-
 				// layout bottom component
-				if( trailingComponent != null ) {
+				if( trailingComponent != null )
-					// trailing component fills all available vertical space
-					int bottomHeight = (rects.length > 0)
-						? ty + th - (rects[rects.length-1].y + rects[rects.length-1].height)
-							- (tabAreaInsets.bottom - trailingComponent.getPreferredSize().height)
-						: th;
 					trailingComponent.setBounds( tx, ty + th - bottomHeight, tw, bottomHeight );
-				}
 			}
 		}
 	}
@@ -2045,7 +2171,8 @@ public class FlatTabbedPaneUI
 			Rectangle bounds = tabPane.getBounds();
 			Insets insets = tabPane.getInsets();
 			int tabPlacement = tabPane.getTabPlacement();
-			Insets tabAreaInsets = getTabAreaInsets( tabPlacement );
+			int tabAreaAlignment = getTabAreaAlignment();
+			Insets tabAreaInsets = getRealTabAreaInsets( tabPlacement );
 			Dimension moreButtonSize = useMoreButton ? moreTabsButton.getPreferredSize() : null;
 			Dimension backwardButtonSize = useMoreButton ? null : backwardButton.getPreferredSize();
 			Dimension forwardButtonSize = useMoreButton ? null : forwardButton.getPreferredSize();
@@ -2071,7 +2198,9 @@ public class FlatTabbedPaneUI
 				// tab area height (maxTabHeight is zero if tab count is zero)
 				int tabAreaHeight = (maxTabHeight > 0)
 					? maxTabHeight
-					: Math.max( calculateMaxExtrasHeight(), scale( clientPropertyInt( tabPane, TABBED_PANE_TAB_HEIGHT, tabHeight ) ) );
+					: Math.max(
+						Math.max( getLeadingPreferredHeight(), getTrailingPreferredHeight() ),
+						scale( clientPropertyInt( tabPane, TABBED_PANE_TAB_HEIGHT, tabHeight ) ) );
 
 				// tab area bounds
 				int tx = insets.left;
@@ -2081,54 +2210,56 @@ public class FlatTabbedPaneUI
 				int tw = bounds.width - insets.left - insets.right;
 				int th = tabAreaHeight;
 
+				int leadingWidth = getLeadingPreferredWidth();
+				int trailingWidth = getTrailingPreferredWidth();
+				int availWidth = tw - leadingWidth - trailingWidth - tabAreaInsets.left - tabAreaInsets.right;
+				int totalTabWidth = (rects.length > 0) ? rectsTotalWidth( leftToRight ) : 0;
+
+				// apply tab area alignment
+				if( totalTabWidth < availWidth && rects.length > 0 ) {
+					int diff = availWidth - totalTabWidth;
+					switch( tabAreaAlignment ) {
+						case ALIGN_LEADING:
+							trailingWidth += diff;
+							break;
+
+						case ALIGN_TRAILING:
+							leadingWidth += diff;
+							break;
+
+						case ALIGN_CENTER:
+							leadingWidth += diff / 2;
+							trailingWidth += diff - (diff / 2);
+							break;
+
+						case ALIGN_FILL:
+							stretchTabsWidth( diff, leftToRight );
+							totalTabWidth = rectsTotalWidth( leftToRight );
+							break;
+					}
+				} else if( rects.length == 0 )
+					trailingWidth = tw - leadingWidth;
+
 				// layout left component
 				Container leftComponent = leftToRight ? leadingComponent : trailingComponent;
-				if( leftComponent != null ) {
+				int leftWidth = leftToRight ? leadingWidth : trailingWidth;
-					int leftWidth = leftComponent.getPreferredSize().width;
+				if( leftComponent != null )
-					if( !leftToRight ) {
-						// trailing component fills all available horizontal space
-						int leadingWidth = (leadingComponent != null) ? leadingComponent.getPreferredSize().width : 0;
-						leftWidth = Math.max( leftWidth, (rects.length > 0)
-							? tw - leadingWidth - (rects[0].x + rects[0].width - rects[rects.length-1].x)
-								- (tabAreaInsets.left + tabAreaInsets.right)
-							: tw - leadingWidth );
-					}
 					leftComponent.setBounds( tx, ty, leftWidth, th );
 
-					// reduce tab area bounds
-					tx += leftWidth;
-					tw -= leftWidth;
-				}
-
 				// layout right component
 				Container rightComponent = leftToRight ? trailingComponent : leadingComponent;
-				if( rightComponent != null ) {
+				int rightWidth = leftToRight ? trailingWidth : leadingWidth;
-					int rightWidth = rightComponent.getPreferredSize().width;
+				if( rightComponent != null )
-					if( leftToRight ) {
-						// trailing component fills all available horizontal space
-						rightWidth = Math.max( rightWidth, (rects.length > 0)
-							? tw - (rects[rects.length-1].x + rects[rects.length-1].width)
-								- (tabAreaInsets.left + tabAreaInsets.right)
-							: tw );
-					}
 					rightComponent.setBounds( tx + tw - rightWidth, ty, rightWidth, th );
 
-					// reduce tab area bounds
-					tw -= rightWidth;
-				}
-
 				// layout tab viewport and buttons
 				if( rects.length > 0 ) {
-					int txi = tx + (leftToRight ? tabAreaInsets.left : tabAreaInsets.right);
+					int txi = tx + leftWidth + (leftToRight ? tabAreaInsets.left : tabAreaInsets.right);
-					int twi = tw - tabAreaInsets.left - tabAreaInsets.right;
+					int twi = tw - leftWidth - rightWidth - tabAreaInsets.left - tabAreaInsets.right;
 
 					// layout viewport and buttons
 					int viewportWidth = twi;
-					Rectangle lastRect = rects[rects.length - 1];
+					if( viewportWidth < totalTabWidth ) {
-					int tabsWidth = leftToRight
-						? (lastRect.x + lastRect.width)
-						: (rects[0].x + rects[0].width - lastRect.x);
-					if( viewportWidth < tabsWidth ) {
 						// need buttons
 						buttonsVisible = true;
 						int buttonsWidth = useMoreButton ? moreButtonSize.width : (backwardButtonSize.width + forwardButtonSize.width);
@@ -2154,7 +2285,9 @@ public class FlatTabbedPaneUI
 				}
 			} else { // LEFT and RIGHT tab placement
 				// tab area width (maxTabWidth is zero if tab count is zero)
-				int tabAreaWidth = (maxTabWidth > 0) ? maxTabWidth : calculateMaxExtrasWidth();
+				int tabAreaWidth = (maxTabWidth > 0)
+					? maxTabWidth
+					: Math.max( getLeadingPreferredWidth(), getTrailingPreferredWidth() );
 
 				// tab area bounds
 				int tx = (tabPlacement == LEFT)
@@ -2164,40 +2297,52 @@ public class FlatTabbedPaneUI
 				int tw = tabAreaWidth;
 				int th = bounds.height - insets.top - insets.bottom;
 
+				int topHeight = getLeadingPreferredHeight();
+				int bottomHeight = getTrailingPreferredHeight();
+				int availHeight = th - topHeight - bottomHeight - tabAreaInsets.top - tabAreaInsets.bottom;
+				int totalTabHeight = (rects.length > 0) ? rectsTotalHeight() : 0;
+
+				// apply tab area alignment
+				if( totalTabHeight < availHeight && rects.length > 0 ) {
+					int diff = availHeight - totalTabHeight;
+					switch( tabAreaAlignment ) {
+						case ALIGN_LEADING:
+							bottomHeight += diff;
+							break;
+
+						case ALIGN_TRAILING:
+							topHeight += diff;
+							break;
+
+						case ALIGN_CENTER:
+							topHeight += diff / 2;
+							bottomHeight += diff - (diff / 2);
+							break;
+
+						case ALIGN_FILL:
+							stretchTabsHeight( diff );
+							totalTabHeight = rectsTotalHeight();
+							break;
+					}
+				} else if( rects.length == 0 )
+					bottomHeight = th - topHeight;
+
 				// layout top component
-				if( leadingComponent != null ) {
+				if( leadingComponent != null )
-					int topHeight = leadingComponent.getPreferredSize().height;
 					leadingComponent.setBounds( tx, ty, tw, topHeight );
 
-					// reduce tab area bounds
-					ty += topHeight;
-					th -= topHeight;
-				}
-
 				// layout bottom component
-				if( trailingComponent != null ) {
+				if( trailingComponent != null )
-					int bottomHeight = trailingComponent.getPreferredSize().height;
-					// trailing component fills all available vertical space
-					bottomHeight = Math.max( bottomHeight, (rects.length > 0)
-						? th - (rects[rects.length-1].y + rects[rects.length-1].height)
-							- (tabAreaInsets.top + tabAreaInsets.bottom)
-						: th );
 					trailingComponent.setBounds( tx, ty + th - bottomHeight, tw, bottomHeight );
 
-					// reduce tab area bounds
-					th -= bottomHeight;
-				}
-
 				// layout tab viewport and buttons
 				if( rects.length > 0 ) {
-					int tyi = ty + tabAreaInsets.top;
+					int tyi = ty + topHeight + tabAreaInsets.top;
-					int thi = th - tabAreaInsets.top - tabAreaInsets.bottom;
+					int thi = th - topHeight - bottomHeight - tabAreaInsets.top - tabAreaInsets.bottom;
 
 					// layout viewport and buttons
 					int viewportHeight = thi;
-					Rectangle lastRect = rects[rects.length - 1];
+					if( viewportHeight < totalTabHeight ) {
-					int tabsHeight = lastRect.y + lastRect.height;
-					if( viewportHeight < tabsHeight ) {
 						// need buttons
 						buttonsVisible = true;
 						int buttonsHeight = useMoreButton ? moreButtonSize.height : (backwardButtonSize.height + forwardButtonSize.height);

flatlaf-core/src/main/resources/com/formdev/flatlaf/FlatLaf.properties

@@ -551,6 +551,7 @@ TabbedPane.disabledForeground=@disabledText
 TabbedPane.shadow=@background
 TabbedPane.contentBorderInsets=null
 TabbedPane.hiddenTabsNavigation=moreTabsButton
+TabbedPane.tabAreaAlignment=leading
 
 TabbedPane.closeIcon=com.formdev.flatlaf.icons.FlatTabbedPaneCloseIcon
 TabbedPane.closeSize=16,16

flatlaf-testing/dumps/uidefaults/FlatDarkLaf_1.8.0_202.txt

@@ -937,6 +937,7 @@ TabbedPane.selectedTabPadInsets 0,0,0,0    javax.swing.plaf.InsetsUIResource [UI
 TabbedPane.selectionFollowsFocus true
 TabbedPane.shadow              #3c3f41    javax.swing.plaf.ColorUIResource [UI]
 TabbedPane.showTabSeparators   false
+TabbedPane.tabAreaAlignment    leading
 TabbedPane.tabAreaInsets       0,0,0,0    javax.swing.plaf.InsetsUIResource [UI]
 TabbedPane.tabHeight           32
 TabbedPane.tabInsets           4,12,4,12    javax.swing.plaf.InsetsUIResource [UI]

flatlaf-testing/dumps/uidefaults/FlatLightLaf_1.8.0_202.txt

@@ -942,6 +942,7 @@ TabbedPane.selectedTabPadInsets 0,0,0,0    javax.swing.plaf.InsetsUIResource [UI
 TabbedPane.selectionFollowsFocus true
 TabbedPane.shadow              #f2f2f2    javax.swing.plaf.ColorUIResource [UI]
 TabbedPane.showTabSeparators   false
+TabbedPane.tabAreaAlignment    leading
 TabbedPane.tabAreaInsets       0,0,0,0    javax.swing.plaf.InsetsUIResource [UI]
 TabbedPane.tabHeight           32
 TabbedPane.tabInsets           4,12,4,12    javax.swing.plaf.InsetsUIResource [UI]

flatlaf-testing/dumps/uidefaults/FlatTestLaf_1.8.0_202.txt

@@ -932,6 +932,7 @@ TabbedPane.selectedTabPadInsets 0,0,0,0    javax.swing.plaf.InsetsUIResource [UI
 TabbedPane.selectionFollowsFocus true
 TabbedPane.shadow              #ccffcc    javax.swing.plaf.ColorUIResource [UI]
 TabbedPane.showTabSeparators   false
+TabbedPane.tabAreaAlignment    leading
 TabbedPane.tabAreaInsets       0,0,0,0    javax.swing.plaf.InsetsUIResource [UI]
 TabbedPane.tabHeight           32
 TabbedPane.tabInsets           4,12,4,12    javax.swing.plaf.InsetsUIResource [UI]

flatlaf-testing/src/main/java/com/formdev/flatlaf/testing/FlatContainerTest.java

@@ -112,6 +112,8 @@ public class FlatContainerTest
 		}
 
 		customTabsChanged( tabbedPane );
+		tabBackForegroundChanged( tabbedPane );
+		setTabIcons( tabbedPane );
 	}
 
 	private void addTab( JTabbedPane tabbedPane ) {
@@ -154,24 +156,26 @@ public class FlatContainerTest
 	}
 
 	private void tabIconsChanged() {
-		boolean showTabIcons = tabIconsCheckBox.isSelected();
+		setTabIcons( tabbedPane1 );
+		setTabIcons( tabbedPane2 );
+		setTabIcons( tabbedPane3 );
+		setTabIcons( tabbedPane4 );
 
-		setTabIcons( tabbedPane1, showTabIcons );
+		tabIconSizeSpinner.setEnabled( tabIconsCheckBox.isSelected() );
-		setTabIcons( tabbedPane2, showTabIcons );
-		setTabIcons( tabbedPane3, showTabIcons );
-		setTabIcons( tabbedPane4, showTabIcons );
-
-		tabIconSizeSpinner.setEnabled( showTabIcons );
 	}
 
-	private void setTabIcons( JTabbedPane tabbedPane, boolean showTabIcons ) {
+	private void setTabIcons( JTabbedPane tabbedPane ) {
+		boolean showTabIcons = tabIconsCheckBox.isSelected();
 		Object iconSize = tabIconSizeSpinner.getValue();
 
 		Icon icon = showTabIcons
 			? new ScaledImageIcon( new ImageIcon( getClass().getResource( "/com/formdev/flatlaf/testing/test" + iconSize + ".png" ) ) )
 			: null;
-		tabbedPane.setIconAt( 0, icon );
+		int tabCount = tabbedPane.getTabCount();
-		tabbedPane.setIconAt( 1, icon );
+		if( tabCount > 0 )
+			tabbedPane.setIconAt( 0, icon );
+		if( tabCount > 1 )
+			tabbedPane.setIconAt( 1, icon );
 	}
 
 	private void customBorderChanged() {
@@ -195,11 +199,11 @@ public class FlatContainerTest
 	private void customTabsChanged( JTabbedPane tabbedPane ) {
 		boolean customTabs = customTabsCheckBox.isSelected();
 		int tabCount = tabbedPane.getTabCount();
-		if( tabCount >= 2 )
+		if( tabCount > 1 )
 			tabbedPane.setTabComponentAt( 1, customTabs ? new JButton( tabbedPane.getTitleAt( 1 ) ) : null );
-		if( tabCount >= 4 )
+		if( tabCount > 3 )
 			tabbedPane.setTabComponentAt( 3, customTabs ? createCustomTab( tabbedPane.getTitleAt( 3 ) ) : null );
-		if( tabCount >= 6 )
+		if( tabCount > 5 )
 			tabbedPane.setTabComponentAt( 5, customTabs ? new JCheckBox( tabbedPane.getTitleAt( 5 ) ) : null );
 	}
 
@@ -235,19 +239,33 @@ public class FlatContainerTest
 	}
 
 	private void hiddenTabsNavigationChanged() {
-		String value = null;
+		String value = (String) hiddenTabsNavigationField.getSelectedItem();
-		switch( (String) hiddenTabsNavigationField.getSelectedItem() ) {
+		if( "default".equals( value ) )
-			case "moreTabsButton":	value = TABBED_PANE_HIDDEN_TABS_NAVIGATION_MORE_TABS_BUTTON; break;
+			value = null;
-			case "arrowButtons":	value = TABBED_PANE_HIDDEN_TABS_NAVIGATION_ARROW_BUTTONS; break;
-		}
-
 		putTabbedPanesClientProperty( TABBED_PANE_HIDDEN_TABS_NAVIGATION, value );
 	}
 
+	private void tabAreaAlignmentChanged() {
+		String value = (String) tabAreaAlignmentField.getSelectedItem();
+		if( "default".equals( value ) )
+			value = null;
+		putTabbedPanesClientProperty( TABBED_PANE_TAB_AREA_ALIGNMENT, value );
+	}
+
 	private void tabBackForegroundChanged() {
+		tabBackForegroundChanged( tabbedPane1 );
+		tabBackForegroundChanged( tabbedPane2 );
+		tabBackForegroundChanged( tabbedPane3 );
+		tabBackForegroundChanged( tabbedPane4 );
+	}
+
+	private void tabBackForegroundChanged( JTabbedPane tabbedPane ) {
 		boolean enabled = tabBackForegroundCheckBox.isSelected();
-		tabbedPane1.setBackgroundAt( 0, enabled ? Color.red : null );
+		int tabCount = tabbedPane.getTabCount();
-		tabbedPane1.setForegroundAt( 1, enabled ? Color.red : null );
+		if( tabCount > 0 )
+			tabbedPane.setBackgroundAt( 0, enabled ? Color.red : null );
+		if( tabCount > 1 )
+			tabbedPane.setForegroundAt( 1, enabled ? Color.red : null );
 	}
 
 	private void leadingComponentChanged() {
@@ -293,13 +311,15 @@ public class FlatContainerTest
 
 		JTabbedPane[] tabbedPanes = new JTabbedPane[] { tabbedPane1, tabbedPane2, tabbedPane3, tabbedPane4 };
 		for( JTabbedPane tabbedPane : tabbedPanes ) {
-			Component c = tabbedPane.getComponentAt( 1 );
+			if( tabbedPane.getTabCount() > 1 ) {
-			((JComponent)c).putClientProperty( TABBED_PANE_TAB_CLOSABLE, value );
+				Component c = tabbedPane.getComponentAt( 1 );
+				((JComponent)c).putClientProperty( TABBED_PANE_TAB_CLOSABLE, value );
+			}
 		}
 	}
 
 	private void tabAreaInsetsChanged() {
-		UIManager.put( "TabbedPane.tabAreaInsets", tabAreaInsetsCheckBox.isSelected() ? new Insets( 10, 10, 25, 25 ) : null );
+		UIManager.put( "TabbedPane.tabAreaInsets", tabAreaInsetsCheckBox.isSelected() ? new Insets( 5, 5, 10, 10 ) : null );
 		FlatLaf.updateUI();
 	}
 
@@ -318,8 +338,10 @@ public class FlatContainerTest
 
 		JTabbedPane[] tabbedPanes = new JTabbedPane[] { tabbedPane1, tabbedPane2, tabbedPane3, tabbedPane4 };
 		for( JTabbedPane tabbedPane : tabbedPanes ) {
-			Component c = tabbedPane.getComponentAt( 1 );
+			if( tabbedPane.getTabCount() > 1 ) {
-			((JComponent)c).putClientProperty( TABBED_PANE_TAB_INSETS, insets );
+				Component c = tabbedPane.getComponentAt( 1 );
+				((JComponent)c).putClientProperty( TABBED_PANE_TAB_INSETS, insets );
+			}
 		}
 	}
 
@@ -363,6 +385,8 @@ public class FlatContainerTest
 		tabPlacementField = new JComboBox<>();
 		tabIconsCheckBox = new JCheckBox();
 		tabIconSizeSpinner = new JSpinner();
+		JLabel tabAreaAlignmentLabel = new JLabel();
+		tabAreaAlignmentField = new JComboBox<>();
 		tabsClosableCheckBox = new JCheckBox();
 		customBorderCheckBox = new JCheckBox();
 		tabAreaInsetsCheckBox = new JCheckBox();
@@ -488,6 +512,7 @@ public class FlatContainerTest
 					// rows
 					"[center]" +
 					"[]" +
+					"[]" +
 					"[]para" +
 					"[]" +
 					"[]para" +
@@ -560,75 +585,90 @@ public class FlatContainerTest
 				tabIconSizeSpinner.addChangeListener(e -> tabIconsChanged());
 				tabbedPaneControlPanel.add(tabIconSizeSpinner, "cell 2 2");
 
+				//---- tabAreaAlignmentLabel ----
+				tabAreaAlignmentLabel.setText("Tab area alignment:");
+				tabbedPaneControlPanel.add(tabAreaAlignmentLabel, "cell 0 3");
+
+				//---- tabAreaAlignmentField ----
+				tabAreaAlignmentField.setModel(new DefaultComboBoxModel<>(new String[] {
+					"default",
+					"leading",
+					"trailing",
+					"center",
+					"fill"
+				}));
+				tabAreaAlignmentField.addActionListener(e -> tabAreaAlignmentChanged());
+				tabbedPaneControlPanel.add(tabAreaAlignmentField, "cell 1 3");
+
 				//---- tabsClosableCheckBox ----
 				tabsClosableCheckBox.setText("Tabs closable");
 				tabsClosableCheckBox.addActionListener(e -> tabsClosableChanged());
-				tabbedPaneControlPanel.add(tabsClosableCheckBox, "cell 0 3");
+				tabbedPaneControlPanel.add(tabsClosableCheckBox, "cell 0 4");
 
 				//---- customBorderCheckBox ----
 				customBorderCheckBox.setText("Custom border");
 				customBorderCheckBox.addActionListener(e -> customBorderChanged());
-				tabbedPaneControlPanel.add(customBorderCheckBox, "cell 1 3");
+				tabbedPaneControlPanel.add(customBorderCheckBox, "cell 1 4");
 
 				//---- tabAreaInsetsCheckBox ----
-				tabAreaInsetsCheckBox.setText("Tab area insets (10,10,25,25)");
+				tabAreaInsetsCheckBox.setText("Tab area insets (5,5,10,10)");
 				tabAreaInsetsCheckBox.addActionListener(e -> tabAreaInsetsChanged());
-				tabbedPaneControlPanel.add(tabAreaInsetsCheckBox, "cell 2 3");
+				tabbedPaneControlPanel.add(tabAreaInsetsCheckBox, "cell 2 4");
 
 				//---- secondTabClosableCheckBox ----
 				secondTabClosableCheckBox.setText("Second Tab closable");
 				secondTabClosableCheckBox.addActionListener(e -> secondTabClosableChanged());
-				tabbedPaneControlPanel.add(secondTabClosableCheckBox, "cell 0 4");
+				tabbedPaneControlPanel.add(secondTabClosableCheckBox, "cell 0 5");
 
 				//---- hasFullBorderCheckBox ----
 				hasFullBorderCheckBox.setText("Show content border");
 				hasFullBorderCheckBox.addActionListener(e -> hasFullBorderChanged());
-				tabbedPaneControlPanel.add(hasFullBorderCheckBox, "cell 1 4,alignx left,growx 0");
+				tabbedPaneControlPanel.add(hasFullBorderCheckBox, "cell 1 5,alignx left,growx 0");
 
 				//---- smallerTabHeightCheckBox ----
 				smallerTabHeightCheckBox.setText("Smaller tab height (26)");
 				smallerTabHeightCheckBox.addActionListener(e -> smallerTabHeightChanged());
-				tabbedPaneControlPanel.add(smallerTabHeightCheckBox, "cell 2 4");
+				tabbedPaneControlPanel.add(smallerTabHeightCheckBox, "cell 2 5");
 
 				//---- leadingComponentCheckBox ----
 				leadingComponentCheckBox.setText("Leading component");
 				leadingComponentCheckBox.addActionListener(e -> leadingComponentChanged());
-				tabbedPaneControlPanel.add(leadingComponentCheckBox, "cell 0 5");
+				tabbedPaneControlPanel.add(leadingComponentCheckBox, "cell 0 6");
 
 				//---- hideContentSeparatorCheckBox ----
 				hideContentSeparatorCheckBox.setText("Hide content separator");
 				hideContentSeparatorCheckBox.addActionListener(e -> hideContentSeparatorChanged());
-				tabbedPaneControlPanel.add(hideContentSeparatorCheckBox, "cell 1 5");
+				tabbedPaneControlPanel.add(hideContentSeparatorCheckBox, "cell 1 6");
 
 				//---- smallerInsetsCheckBox ----
 				smallerInsetsCheckBox.setText("Smaller tab insets (2,2,2,2)");
 				smallerInsetsCheckBox.addActionListener(e -> smallerInsetsChanged());
-				tabbedPaneControlPanel.add(smallerInsetsCheckBox, "cell 2 5");
+				tabbedPaneControlPanel.add(smallerInsetsCheckBox, "cell 2 6");
 
 				//---- trailingComponentCheckBox ----
 				trailingComponentCheckBox.setText("Trailing component");
 				trailingComponentCheckBox.addActionListener(e -> trailingComponentChanged());
-				tabbedPaneControlPanel.add(trailingComponentCheckBox, "cell 0 6");
+				tabbedPaneControlPanel.add(trailingComponentCheckBox, "cell 0 7");
 
 				//---- showTabSeparatorsCheckBox ----
 				showTabSeparatorsCheckBox.setText("Show tab separators");
 				showTabSeparatorsCheckBox.addActionListener(e -> showTabSeparatorsChanged());
-				tabbedPaneControlPanel.add(showTabSeparatorsCheckBox, "cell 1 6");
+				tabbedPaneControlPanel.add(showTabSeparatorsCheckBox, "cell 1 7");
 
 				//---- secondTabWiderCheckBox ----
 				secondTabWiderCheckBox.setText("Second Tab insets wider (4,20,4,20)");
 				secondTabWiderCheckBox.addActionListener(e -> secondTabWiderChanged());
-				tabbedPaneControlPanel.add(secondTabWiderCheckBox, "cell 2 6");
+				tabbedPaneControlPanel.add(secondTabWiderCheckBox, "cell 2 7");
 
 				//---- minimumTabWidthCheckBox ----
 				minimumTabWidthCheckBox.setText("Minimum tab width (100)");
 				minimumTabWidthCheckBox.addActionListener(e -> minimumTabWidthChanged());
-				tabbedPaneControlPanel.add(minimumTabWidthCheckBox, "cell 2 7");
+				tabbedPaneControlPanel.add(minimumTabWidthCheckBox, "cell 2 8");
 
 				//---- maximumTabWidthCheckBox ----
 				maximumTabWidthCheckBox.setText("Maximum tab width (60)");
 				maximumTabWidthCheckBox.addActionListener(e -> maximumTabWidthChanged());
-				tabbedPaneControlPanel.add(maximumTabWidthCheckBox, "cell 2 8");
+				tabbedPaneControlPanel.add(maximumTabWidthCheckBox, "cell 2 9");
 			}
 			panel9.add(tabbedPaneControlPanel, cc.xywh(1, 11, 3, 1));
 		}
@@ -649,6 +689,7 @@ public class FlatContainerTest
 	private JComboBox<String> tabPlacementField;
 	private JCheckBox tabIconsCheckBox;
 	private JSpinner tabIconSizeSpinner;
+	private JComboBox<String> tabAreaAlignmentField;
 	private JCheckBox tabsClosableCheckBox;
 	private JCheckBox customBorderCheckBox;
 	private JCheckBox tabAreaInsetsCheckBox;

flatlaf-testing/src/main/java/com/formdev/flatlaf/testing/FlatContainerTest.jfd

@@ -132,7 +132,7 @@ new FormModel {
 				add( new FormContainer( "com.formdev.flatlaf.testing.FlatTestFrame$NoRightToLeftPanel", new FormLayoutManager( class net.miginfocom.swing.MigLayout ) {
 					"$layoutConstraints": "insets 0,hidemode 3"
 					"$columnConstraints": "[][fill][]"
-					"$rowConstraints": "[center][][]para[][]para[][]para[][]"
+					"$rowConstraints": "[center][][][]para[][]para[][]para[][]"
 				} ) {
 					name: "tabbedPaneControlPanel"
 					"opaque": false
@@ -261,6 +261,30 @@ new FormModel {
 					}, new FormLayoutConstraints( class net.miginfocom.layout.CC ) {
 						"value": "cell 2 2"
 					} )
+					add( new FormComponent( "javax.swing.JLabel" ) {
+						name: "tabAreaAlignmentLabel"
+						"text": "Tab area alignment:"
+					}, new FormLayoutConstraints( class net.miginfocom.layout.CC ) {
+						"value": "cell 0 3"
+					} )
+					add( new FormComponent( "javax.swing.JComboBox" ) {
+						name: "tabAreaAlignmentField"
+						"model": new javax.swing.DefaultComboBoxModel {
+							selectedItem: "default"
+							addElement( "default" )
+							addElement( "leading" )
+							addElement( "trailing" )
+							addElement( "center" )
+							addElement( "fill" )
+						}
+						auxiliary() {
+							"JavaCodeGenerator.variableLocal": false
+							"JavaCodeGenerator.typeParameters": "String"
+						}
+						addEvent( new FormEvent( "java.awt.event.ActionListener", "actionPerformed", "tabAreaAlignmentChanged", false ) )
+					}, new FormLayoutConstraints( class net.miginfocom.layout.CC ) {
+						"value": "cell 1 3"
+					} )
 					add( new FormComponent( "javax.swing.JCheckBox" ) {
 						name: "tabsClosableCheckBox"
 						"text": "Tabs closable"
@@ -269,7 +293,7 @@ new FormModel {
 						}
 						addEvent( new FormEvent( "java.awt.event.ActionListener", "actionPerformed", "tabsClosableChanged", false ) )
 					}, new FormLayoutConstraints( class net.miginfocom.layout.CC ) {
-						"value": "cell 0 3"
+						"value": "cell 0 4"
 					} )
 					add( new FormComponent( "javax.swing.JCheckBox" ) {
 						name: "customBorderCheckBox"
@@ -279,17 +303,17 @@ new FormModel {
 						}
 						addEvent( new FormEvent( "java.awt.event.ActionListener", "actionPerformed", "customBorderChanged", false ) )
 					}, new FormLayoutConstraints( class net.miginfocom.layout.CC ) {
-						"value": "cell 1 3"
+						"value": "cell 1 4"
 					} )
 					add( new FormComponent( "javax.swing.JCheckBox" ) {
 						name: "tabAreaInsetsCheckBox"
-						"text": "Tab area insets (10,10,25,25)"
+						"text": "Tab area insets (5,5,10,10)"
 						auxiliary() {
 							"JavaCodeGenerator.variableLocal": false
 						}
 						addEvent( new FormEvent( "java.awt.event.ActionListener", "actionPerformed", "tabAreaInsetsChanged", false ) )
 					}, new FormLayoutConstraints( class net.miginfocom.layout.CC ) {
-						"value": "cell 2 3"
+						"value": "cell 2 4"
 					} )
 					add( new FormComponent( "com.formdev.flatlaf.extras.TriStateCheckBox" ) {
 						name: "secondTabClosableCheckBox"
@@ -299,7 +323,7 @@ new FormModel {
 						}
 						addEvent( new FormEvent( "java.awt.event.ActionListener", "actionPerformed", "secondTabClosableChanged", false ) )
 					}, new FormLayoutConstraints( class net.miginfocom.layout.CC ) {
-						"value": "cell 0 4"
+						"value": "cell 0 5"
 					} )
 					add( new FormComponent( "javax.swing.JCheckBox" ) {
 						name: "hasFullBorderCheckBox"
@@ -309,7 +333,7 @@ new FormModel {
 						}
 						addEvent( new FormEvent( "java.awt.event.ActionListener", "actionPerformed", "hasFullBorderChanged", false ) )
 					}, new FormLayoutConstraints( class net.miginfocom.layout.CC ) {
-						"value": "cell 1 4,alignx left,growx 0"
+						"value": "cell 1 5,alignx left,growx 0"
 					} )
 					add( new FormComponent( "javax.swing.JCheckBox" ) {
 						name: "smallerTabHeightCheckBox"
@@ -319,7 +343,7 @@ new FormModel {
 						}
 						addEvent( new FormEvent( "java.awt.event.ActionListener", "actionPerformed", "smallerTabHeightChanged", false ) )
 					}, new FormLayoutConstraints( class net.miginfocom.layout.CC ) {
-						"value": "cell 2 4"
+						"value": "cell 2 5"
 					} )
 					add( new FormComponent( "javax.swing.JCheckBox" ) {
 						name: "leadingComponentCheckBox"
@@ -329,7 +353,7 @@ new FormModel {
 						}
 						addEvent( new FormEvent( "java.awt.event.ActionListener", "actionPerformed", "leadingComponentChanged", false ) )
 					}, new FormLayoutConstraints( class net.miginfocom.layout.CC ) {
-						"value": "cell 0 5"
+						"value": "cell 0 6"
 					} )
 					add( new FormComponent( "javax.swing.JCheckBox" ) {
 						name: "hideContentSeparatorCheckBox"
@@ -339,7 +363,7 @@ new FormModel {
 						}
 						addEvent( new FormEvent( "java.awt.event.ActionListener", "actionPerformed", "hideContentSeparatorChanged", false ) )
 					}, new FormLayoutConstraints( class net.miginfocom.layout.CC ) {
-						"value": "cell 1 5"
+						"value": "cell 1 6"
 					} )
 					add( new FormComponent( "javax.swing.JCheckBox" ) {
 						name: "smallerInsetsCheckBox"
@@ -349,7 +373,7 @@ new FormModel {
 						}
 						addEvent( new FormEvent( "java.awt.event.ActionListener", "actionPerformed", "smallerInsetsChanged", false ) )
 					}, new FormLayoutConstraints( class net.miginfocom.layout.CC ) {
-						"value": "cell 2 5"
+						"value": "cell 2 6"
 					} )
 					add( new FormComponent( "javax.swing.JCheckBox" ) {
 						name: "trailingComponentCheckBox"
@@ -359,7 +383,7 @@ new FormModel {
 						}
 						addEvent( new FormEvent( "java.awt.event.ActionListener", "actionPerformed", "trailingComponentChanged", false ) )
 					}, new FormLayoutConstraints( class net.miginfocom.layout.CC ) {
-						"value": "cell 0 6"
+						"value": "cell 0 7"
 					} )
 					add( new FormComponent( "javax.swing.JCheckBox" ) {
 						name: "showTabSeparatorsCheckBox"
@@ -369,7 +393,7 @@ new FormModel {
 						}
 						addEvent( new FormEvent( "java.awt.event.ActionListener", "actionPerformed", "showTabSeparatorsChanged", false ) )
 					}, new FormLayoutConstraints( class net.miginfocom.layout.CC ) {
-						"value": "cell 1 6"
+						"value": "cell 1 7"
 					} )
 					add( new FormComponent( "javax.swing.JCheckBox" ) {
 						name: "secondTabWiderCheckBox"
@@ -379,7 +403,7 @@ new FormModel {
 						}
 						addEvent( new FormEvent( "java.awt.event.ActionListener", "actionPerformed", "secondTabWiderChanged", false ) )
 					}, new FormLayoutConstraints( class net.miginfocom.layout.CC ) {
-						"value": "cell 2 6"
+						"value": "cell 2 7"
 					} )
 					add( new FormComponent( "javax.swing.JCheckBox" ) {
 						name: "minimumTabWidthCheckBox"
@@ -389,7 +413,7 @@ new FormModel {
 						}
 						addEvent( new FormEvent( "java.awt.event.ActionListener", "actionPerformed", "minimumTabWidthChanged", false ) )
 					}, new FormLayoutConstraints( class net.miginfocom.layout.CC ) {
-						"value": "cell 2 7"
+						"value": "cell 2 8"
 					} )
 					add( new FormComponent( "javax.swing.JCheckBox" ) {
 						name: "maximumTabWidthCheckBox"
@@ -399,7 +423,7 @@ new FormModel {
 						}
 						addEvent( new FormEvent( "java.awt.event.ActionListener", "actionPerformed", "maximumTabWidthChanged", false ) )
 					}, new FormLayoutConstraints( class net.miginfocom.layout.CC ) {
-						"value": "cell 2 8"
+						"value": "cell 2 9"
 					} )
 				}, new FormLayoutConstraints( class com.jgoodies.forms.layout.CellConstraints ) {
 					"gridY": 11
@@ -410,7 +434,7 @@ new FormModel {
 			} )
 		}, new FormLayoutConstraints( null ) {
 			"location": new java.awt.Point( 0, 0 )
-			"size": new java.awt.Dimension( 810, 745 )
+			"size": new java.awt.Dimension( 810, 860 )
 		} )
 		add( new FormContainer( "javax.swing.JPanel", new FormLayoutManager( class net.miginfocom.swing.MigLayout ) {
 			"$layoutConstraints": "hidemode 3,align center center"
@@ -440,7 +464,7 @@ new FormModel {
 				"value": "cell 2 0"
 			} )
 		}, new FormLayoutConstraints( null ) {
-			"location": new java.awt.Point( 0, 790 )
+			"location": new java.awt.Point( 0, 890 )
 			"size": new java.awt.Dimension( 291, 118 )
 		} )
 		add( new FormContainer( "javax.swing.JPanel", new FormLayoutManager( class net.miginfocom.swing.MigLayout ) {
@@ -465,7 +489,7 @@ new FormModel {
 				"value": "cell 1 0"
 			} )
 		}, new FormLayoutConstraints( null ) {
-			"location": new java.awt.Point( 340, 790 )
+			"location": new java.awt.Point( 340, 890 )
 			"size": new java.awt.Dimension( 291, 118 )
 		} )
 	}

flatlaf-theme-editor/src/main/resources/com/formdev/flatlaf/themeeditor/FlatLafUIKeys.txt

@@ -667,6 +667,7 @@ TabbedPane.selectedTabPadInsets
 TabbedPane.selectionFollowsFocus
 TabbedPane.shadow
 TabbedPane.showTabSeparators
+TabbedPane.tabAreaAlignment
 TabbedPane.tabAreaInsets
 TabbedPane.tabHeight
 TabbedPane.tabInsets