Menus: changed menu bar and popup menu background colors (made brighter in light themes and darker in dark themes)

made `JMenu`, `JMenuItem`, `JCheckBoxMenuItem` and `JRadioButtonMenuItem` non-opaque

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

@@ -16,7 +16,12 @@
 
 package com.formdev.flatlaf.ui;
 
+import java.awt.Component;
+import java.awt.Container;
+import java.awt.Insets;
+import javax.swing.JScrollPane;
 import javax.swing.UIManager;
+import com.formdev.flatlaf.util.UIScale;
 
 /**
  * Border for {@link javax.swing.JPopupMenu}.
@@ -33,4 +38,18 @@ public class FlatPopupMenuBorder
 		super( UIManager.getInsets( "PopupMenu.borderInsets" ),
 			UIManager.getColor( "PopupMenu.borderColor" ) );
 	}
+
+	@Override
+	public Insets getBorderInsets( Component c, Insets insets ) {
+		if( c instanceof Container &&
+			((Container)c).getComponentCount() > 0 &&
+			((Container)c).getComponent( 0 ) instanceof JScrollPane )
+		{
+			// e.g. for combobox popups
+			insets.left = insets.top = insets.right = insets.bottom = UIScale.scale( 1 );
+			return insets;
+		}
+
+		return super.getBorderInsets( c, insets );
+	}
 }

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

@@ -28,6 +28,7 @@
 @selectionInactiveForeground=@foreground
 @disabledText=#777777
 @textComponentBackground=#45494A
+@menuBackground=darken(@background,5%)
 @cellFocusColor=#000000
 @icon=#adadad
 

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

@@ -121,6 +121,8 @@ CheckBoxMenuItem.border=com.formdev.flatlaf.ui.FlatMarginBorder
 CheckBoxMenuItem.checkIcon=com.formdev.flatlaf.icons.FlatCheckBoxMenuItemIcon
 CheckBoxMenuItem.arrowIcon=com.formdev.flatlaf.icons.FlatMenuItemArrowIcon
 CheckBoxMenuItem.margin=2,2,2,2
+CheckBoxMenuItem.opaque=false
+CheckBoxMenuItem.background=@menuBackground
 
 
 #---- ColorChooser ----
@@ -216,12 +218,15 @@ Menu.border=com.formdev.flatlaf.ui.FlatMarginBorder
 Menu.arrowIcon=com.formdev.flatlaf.icons.FlatMenuArrowIcon
 Menu.margin=2,2,2,2
 Menu.submenuPopupOffsetX={scaledInteger}-4
-Menu.submenuPopupOffsetY={scaledInteger}-1
+Menu.submenuPopupOffsetY={scaledInteger}-4
+Menu.opaque=false
+Menu.background=@menuBackground
 
 
 #---- MenuBar ----
 
 MenuBar.border=com.formdev.flatlaf.ui.FlatMenuBarBorder
+MenuBar.background=@menuBackground
 
 
 #---- MenuItem ----
@@ -229,6 +234,8 @@ MenuBar.border=com.formdev.flatlaf.ui.FlatMenuBarBorder
 MenuItem.border=com.formdev.flatlaf.ui.FlatMarginBorder
 MenuItem.arrowIcon=com.formdev.flatlaf.icons.FlatMenuItemArrowIcon
 MenuItem.margin=2,2,2,2
+MenuItem.opaque=false
+MenuItem.background=@menuBackground
 
 
 #---- OptionPane ----
@@ -265,7 +272,8 @@ PasswordField.placeholderForeground=@disabledText
 #---- PopupMenu ----
 
 PopupMenu.border=com.formdev.flatlaf.ui.FlatPopupMenuBorder
-PopupMenu.borderInsets=1,1,1,1
+PopupMenu.borderInsets=4,1,4,1
+PopupMenu.background=@menuBackground
 
 
 #---- PopupMenuSeparator ----
@@ -299,6 +307,8 @@ RadioButtonMenuItem.border=com.formdev.flatlaf.ui.FlatMarginBorder
 RadioButtonMenuItem.checkIcon=com.formdev.flatlaf.icons.FlatRadioButtonMenuItemIcon
 RadioButtonMenuItem.arrowIcon=com.formdev.flatlaf.icons.FlatMenuItemArrowIcon
 RadioButtonMenuItem.margin=2,2,2,2
+RadioButtonMenuItem.opaque=false
+RadioButtonMenuItem.background=@menuBackground
 
 
 #---- ScrollBar ----

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

@@ -28,6 +28,7 @@
 @selectionInactiveForeground=@foreground
 @disabledText=#8C8C8C
 @textComponentBackground=#ffffff
+@menuBackground=#fff
 @cellFocusColor=#000000
 @icon=#afafaf