refactored some anonymous classes into nested classes for easier extending/subclassing

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

@@ -202,13 +202,7 @@ public class FlatButtonUI
 
 	@Override
 	protected BasicButtonListener createButtonListener( AbstractButton b ) {
-		return new BasicButtonListener( b ) {
+		return new FlatButtonListener( b );
-			@Override
-			public void propertyChange( PropertyChangeEvent e ) {
-				super.propertyChange( e );
-				FlatButtonUI.this.propertyChange( b, e );
-			}
-		};
 	}
 
 	protected void propertyChange( AbstractButton b, PropertyChangeEvent e ) {
@@ -475,4 +469,23 @@ public class FlatButtonUI
 
 		return prefSize;
 	}
+
+	//---- class FlatButtonListener -------------------------------------------
+
+	protected class FlatButtonListener
+		extends BasicButtonListener
+	{
+		private final AbstractButton b;
+
+		protected FlatButtonListener( AbstractButton b ) {
+			super( b );
+			this.b = b;
+		}
+
+		@Override
+		public void propertyChange( PropertyChangeEvent e ) {
+			super.propertyChange( e );
+			FlatButtonUI.this.propertyChange( b, e );
+		}
+	}
 }

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

@@ -119,7 +119,7 @@ public class FlatComboBoxUI
 	protected Color buttonHoverArrowColor;
 
 	private MouseListener hoverListener;
-	private boolean hover;
+	protected boolean hover;
 
 	private WeakReference<Component> lastRendererComponent;
 
@@ -332,14 +332,7 @@ public class FlatComboBoxUI
 
 	@Override
 	protected JButton createArrowButton() {
-		return new FlatArrowButton( SwingConstants.SOUTH, arrowType, buttonArrowColor,
+		return new FlatComboBoxButton();
-			buttonDisabledArrowColor, buttonHoverArrowColor, null )
-		{
-			@Override
-			protected boolean isHover() {
-				return super.isHover() || (!comboBox.isEditable() ? hover : false);
-			}
-		};
 	}
 
 	@Override
@@ -507,6 +500,27 @@ public class FlatComboBoxUI
 		}
 	}
 
+	//---- class FlatComboBoxButton -------------------------------------------
+
+	protected class FlatComboBoxButton
+		extends FlatArrowButton
+	{
+		protected FlatComboBoxButton() {
+			this( SwingConstants.SOUTH, arrowType, buttonArrowColor, buttonDisabledArrowColor, buttonHoverArrowColor, null, null );
+		}
+
+		protected FlatComboBoxButton( int direction, String type, Color foreground, Color disabledForeground,
+			Color hoverForeground, Color hoverBackground, Color pressedBackground )
+		{
+			super( direction, type, foreground, disabledForeground, hoverForeground, hoverBackground, pressedBackground );
+		}
+
+		@Override
+		protected boolean isHover() {
+			return super.isHover() || (!comboBox.isEditable() ? hover : false);
+		}
+	}
+
 	//---- class FlatComboPopup -----------------------------------------------
 
 	@SuppressWarnings( { "rawtypes", "unchecked" } )

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

@@ -150,7 +150,7 @@ public class FlatInternalFrameTitlePane
 
 	//---- class FlatPropertyChangeHandler ------------------------------------
 
-	private class FlatPropertyChangeHandler
+	protected class FlatPropertyChangeHandler
 		extends PropertyChangeHandler
 	{
 		@Override

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

@@ -198,46 +198,12 @@ public class FlatScrollBarUI
 
 	@Override
 	protected JButton createDecreaseButton( int orientation ) {
-		return createArrowButton( orientation );
+		return new FlatScrollBarButton( orientation );
 	}
 
 	@Override
 	protected JButton createIncreaseButton( int orientation ) {
-		return createArrowButton( orientation );
+		return new FlatScrollBarButton( orientation );
-	}
-
-	private JButton createArrowButton( int orientation ) {
-		FlatArrowButton button = new FlatArrowButton( orientation, arrowType, buttonArrowColor,
-			buttonDisabledArrowColor, null, hoverButtonBackground, pressedButtonBackground )
-		{
-			@Override
-			protected Color deriveBackground( Color background ) {
-				return FlatUIUtils.deriveColor( background, scrollbar.getBackground() );
-			}
-
-			@Override
-			public Dimension getPreferredSize() {
-				if( isShowButtons() ) {
-					int w = UIScale.scale( scrollBarWidth );
-					return new Dimension( w, w );
-				} else
-					return new Dimension();
-			}
-
-			@Override
-			public Dimension getMinimumSize() {
-				return isShowButtons() ? super.getMinimumSize() : new Dimension();
-			}
-
-			@Override
-			public Dimension getMaximumSize() {
-				return isShowButtons() ? super.getMaximumSize() : new Dimension();
-			}
-		};
-		button.setArrowWidth( FlatArrowButton.DEFAULT_ARROW_WIDTH - 2 );
-		button.setFocusable( false );
-		button.setRequestFocusEnabled( false );
-		return button;
 	}
 
 	protected boolean isShowButtons() {
@@ -377,4 +343,49 @@ public class FlatScrollBarUI
 				scrollbar.repaint();
 		}
 	}
+
+	//---- class FlatScrollBarButton ------------------------------------------
+
+	protected class FlatScrollBarButton
+		extends FlatArrowButton
+	{
+		protected FlatScrollBarButton( int direction ) {
+			this( direction, arrowType, buttonArrowColor, buttonDisabledArrowColor,
+				null, hoverButtonBackground, pressedButtonBackground );
+		}
+
+		protected FlatScrollBarButton( int direction, String type, Color foreground, Color disabledForeground,
+			Color hoverForeground, Color hoverBackground, Color pressedBackground )
+		{
+			super( direction, type, foreground, disabledForeground, hoverForeground, hoverBackground, pressedBackground );
+
+			setArrowWidth( FlatArrowButton.DEFAULT_ARROW_WIDTH - 2 );
+			setFocusable( false );
+			setRequestFocusEnabled( false );
+		}
+
+		@Override
+		protected Color deriveBackground( Color background ) {
+			return FlatUIUtils.deriveColor( background, scrollbar.getBackground() );
+		}
+
+		@Override
+		public Dimension getPreferredSize() {
+			if( isShowButtons() ) {
+				int w = UIScale.scale( scrollBarWidth );
+				return new Dimension( w, w );
+			} else
+				return new Dimension();
+		}
+
+		@Override
+		public Dimension getMinimumSize() {
+			return isShowButtons() ? super.getMinimumSize() : new Dimension();
+		}
+
+		@Override
+		public Dimension getMaximumSize() {
+			return isShowButtons() ? super.getMaximumSize() : new Dimension();
+		}
+	}
 }

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

@@ -87,10 +87,10 @@ public class FlatSplitPaneUI
 
 	//---- class FlatSplitPaneDivider -----------------------------------------
 
-	private class FlatSplitPaneDivider
+	protected class FlatSplitPaneDivider
 		extends BasicSplitPaneDivider
 	{
-		public FlatSplitPaneDivider( BasicSplitPaneUI ui ) {
+		protected FlatSplitPaneDivider( BasicSplitPaneUI ui ) {
 			super( ui );
 		}