FlatBorder: refractored ComboBox, ScrollPane and Spinner focus owner checking to UI delegates (for later usage)

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

@@ -22,17 +22,12 @@ import java.awt.Component;
 import java.awt.Graphics;
 import java.awt.Graphics2D;
 import java.awt.Insets;
-import java.awt.KeyboardFocusManager;
 import java.awt.Paint;
 import javax.swing.JComboBox;
 import javax.swing.JComponent;
 import javax.swing.JScrollPane;
 import javax.swing.JSpinner;
-import javax.swing.JTable;
-import javax.swing.JTextField;
-import javax.swing.JTree;
 import javax.swing.JViewport;
-import javax.swing.SwingUtilities;
 import javax.swing.UIManager;
 import javax.swing.plaf.basic.BasicBorders;
 import com.formdev.flatlaf.FlatClientProperties;
@@ -164,37 +159,13 @@ public class FlatBorder
 	}
 
 	protected boolean isFocused( Component c ) {
-		if( c instanceof JScrollPane ) {
-			JViewport viewport = ((JScrollPane)c).getViewport();
-			Component view = (viewport != null) ? viewport.getView() : null;
-			if( view != null ) {
-				if( FlatUIUtils.isPermanentFocusOwner( view ) )
-					return true;
-
-				if( (view instanceof JTable && ((JTable)view).isEditing()) ||
-					(view instanceof JTree && ((JTree)view).isEditing()) )
-				{
-					Component focusOwner = KeyboardFocusManager.getCurrentKeyboardFocusManager().getFocusOwner();
-					if( focusOwner != null )
-						return SwingUtilities.isDescendingFrom( focusOwner, view );
-				}
-			}
-			return false;
-		} else if( c instanceof JComboBox && ((JComboBox<?>)c).isEditable() ) {
-			Component editorComponent = ((JComboBox<?>)c).getEditor().getEditorComponent();
-			return (editorComponent != null) ? FlatUIUtils.isPermanentFocusOwner( editorComponent ) : false;
-		} else if( c instanceof JSpinner ) {
-			if( FlatUIUtils.isPermanentFocusOwner( c ) )
-				return true;
-
-			JComponent editor = ((JSpinner)c).getEditor();
-			if( editor instanceof JSpinner.DefaultEditor ) {
-				JTextField textField = ((JSpinner.DefaultEditor)editor).getTextField();
-				if( textField != null )
-					return FlatUIUtils.isPermanentFocusOwner( textField );
-			}
-			return false;
-		} else
+		if( c instanceof JScrollPane )
+			return FlatScrollPaneUI.isPermanentFocusOwner( (JScrollPane) c );
+		else if( c instanceof JComboBox )
+			return FlatComboBoxUI.isPermanentFocusOwner( (JComboBox<?>) c );
+		else if( c instanceof JSpinner )
+			return FlatSpinnerUI.isPermanentFocusOwner( (JSpinner) c );
+		else
 			return FlatUIUtils.isPermanentFocusOwner( c );
 	}
 

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

@@ -590,6 +590,14 @@ public class FlatComboBoxUI
 		return parentParent != null && !comboBox.getBackground().equals( parentParent.getBackground() );
 	}
 
+	public static boolean isPermanentFocusOwner( JComboBox<?> comboBox ) {
+		if( comboBox.isEditable() ) {
+			Component editorComponent = comboBox.getEditor().getEditorComponent();
+			return (editorComponent != null) ? FlatUIUtils.isPermanentFocusOwner( editorComponent ) : false;
+		} else
+			return FlatUIUtils.isPermanentFocusOwner( comboBox );
+	}
+
 	//---- class FlatComboBoxButton -------------------------------------------
 
 	protected class FlatComboBoxButton

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

@@ -19,6 +19,7 @@ package com.formdev.flatlaf.ui;
 import java.awt.Component;
 import java.awt.Graphics;
 import java.awt.Insets;
+import java.awt.KeyboardFocusManager;
 import java.awt.Rectangle;
 import java.awt.event.ContainerEvent;
 import java.awt.event.ContainerListener;
@@ -34,11 +35,13 @@ import javax.swing.JComponent;
 import javax.swing.JScrollBar;
 import javax.swing.JScrollPane;
 import javax.swing.JTable;
+import javax.swing.JTree;
 import javax.swing.JViewport;
 import javax.swing.LookAndFeel;
 import javax.swing.ScrollPaneConstants;
 import javax.swing.Scrollable;
 import javax.swing.SwingConstants;
+import javax.swing.SwingUtilities;
 import javax.swing.UIManager;
 import javax.swing.plaf.ComponentUI;
 import javax.swing.plaf.basic.BasicScrollPaneUI;
@@ -329,6 +332,28 @@ public class FlatScrollPaneUI
 		paint( g, c );
 	}
 
+	public static boolean isPermanentFocusOwner( JScrollPane scrollPane ) {
+		JViewport viewport = scrollPane.getViewport();
+		Component view = (viewport != null) ? viewport.getView() : null;
+		if( view == null )
+			return false;
+
+		// check whether view is focus owner
+		if( FlatUIUtils.isPermanentFocusOwner( view ) )
+			return true;
+
+		// check whether editor component in JTable or JTree is focus owner
+		if( (view instanceof JTable && ((JTable)view).isEditing()) ||
+			(view instanceof JTree && ((JTree)view).isEditing()) )
+		{
+			Component focusOwner = KeyboardFocusManager.getCurrentKeyboardFocusManager().getFocusOwner();
+			if( focusOwner != null )
+				return SwingUtilities.isDescendingFrom( focusOwner, view );
+		}
+
+		return false;
+	}
+
 	//---- class Handler ------------------------------------------------------
 
 	/**
@@ -350,11 +375,13 @@ public class FlatScrollPaneUI
 
 		@Override
 		public void focusGained( FocusEvent e ) {
+			// necessary to update focus border
 			scrollpane.repaint();
 		}
 
 		@Override
 		public void focusLost( FocusEvent e ) {
+			// necessary to update focus border
 			scrollpane.repaint();
 		}
 	}

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

@@ -221,6 +221,16 @@ public class FlatSpinnerUI
 			: null;
 	}
 
+	public static boolean isPermanentFocusOwner( JSpinner spinner ) {
+		if( FlatUIUtils.isPermanentFocusOwner( spinner ) )
+			return true;
+
+		JTextField textField = getEditorTextField( spinner.getEditor() );
+		return (textField != null)
+			? FlatUIUtils.isPermanentFocusOwner( textField )
+			: false;
+	}
+
 	protected Color getBackground( boolean enabled ) {
 		return enabled
 			? spinner.getBackground()