TabbedPane: selected tab underline color now changes depending on whether the focus is within the tab content (issue #398)

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

@@ -618,6 +618,7 @@ public class IntelliJTheme
 		// TabbedPane
 		uiKeyCopying.put( "TabbedPane.selectedBackground",     "DefaultTabs.underlinedTabBackground" );
 		uiKeyCopying.put( "TabbedPane.selectedForeground",     "DefaultTabs.underlinedTabForeground" );
+		uiKeyCopying.put( "TabbedPane.inactiveUnderlineColor", "DefaultTabs.inactiveUnderlineColor" );
 
 		// TitlePane
 		uiKeyCopying.put( "TitlePane.inactiveBackground",     "TitlePane.background" );

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

@@ -59,6 +59,7 @@ import java.util.Map;
 import java.util.Set;
 import java.util.function.BiConsumer;
 import java.util.function.IntConsumer;
+import java.util.function.Predicate;
 import javax.accessibility.Accessible;
 import javax.accessibility.AccessibleContext;
 import javax.swing.Action;
@@ -82,10 +83,12 @@ import javax.swing.event.ChangeListener;
 import javax.swing.event.PopupMenuEvent;
 import javax.swing.event.PopupMenuListener;
 import javax.swing.plaf.ComponentUI;
+import javax.swing.plaf.TabbedPaneUI;
 import javax.swing.plaf.UIResource;
 import javax.swing.plaf.basic.BasicTabbedPaneUI;
 import javax.swing.text.JTextComponent;
 import javax.swing.text.View;
+import com.formdev.flatlaf.FlatClientProperties;
 import com.formdev.flatlaf.FlatLaf;
 import com.formdev.flatlaf.icons.FlatTabbedPaneCloseIcon;
 import com.formdev.flatlaf.ui.FlatStylingSupport.Styleable;
@@ -127,6 +130,7 @@ import com.formdev.flatlaf.util.UIScale;
  * @uiDefault TabbedPane.selectedBackground				Color	optional
  * @uiDefault TabbedPane.selectedForeground				Color
  * @uiDefault TabbedPane.underlineColor					Color
+ * @uiDefault TabbedPane.inactiveUnderlineColor			Color
  * @uiDefault TabbedPane.disabledUnderlineColor			Color
  * @uiDefault TabbedPane.hoverColor						Color
  * @uiDefault TabbedPane.focusColor						Color
@@ -198,6 +202,7 @@ public class FlatTabbedPaneUI
 	@Styleable protected Color selectedBackground;
 	@Styleable protected Color selectedForeground;
 	@Styleable protected Color underlineColor;
+	/** @since 2.2 */ @Styleable protected Color inactiveUnderlineColor;
 	@Styleable protected Color disabledUnderlineColor;
 	@Styleable protected Color hoverColor;
 	@Styleable protected Color focusColor;
@@ -288,6 +293,7 @@ public class FlatTabbedPaneUI
 
 		super.installUI( c );
 
+		FlatSelectedTabRepainter.install();
 		installStyle();
 	}
 
@@ -318,6 +324,7 @@ public class FlatTabbedPaneUI
 		selectedBackground = UIManager.getColor( "TabbedPane.selectedBackground" );
 		selectedForeground = UIManager.getColor( "TabbedPane.selectedForeground" );
 		underlineColor = UIManager.getColor( "TabbedPane.underlineColor" );
+		inactiveUnderlineColor = FlatUIUtils.getUIColor( "TabbedPane.inactiveUnderlineColor", underlineColor );
 		disabledUnderlineColor = UIManager.getColor( "TabbedPane.disabledUnderlineColor" );
 		hoverColor = UIManager.getColor( "TabbedPane.hoverColor" );
 		focusColor = UIManager.getColor( "TabbedPane.focusColor" );
@@ -385,6 +392,7 @@ public class FlatTabbedPaneUI
 		selectedBackground = null;
 		selectedForeground = null;
 		underlineColor = null;
+		inactiveUnderlineColor = null;
 		disabledUnderlineColor = null;
 		hoverColor = null;
 		focusColor = null;
@@ -733,7 +741,6 @@ public class FlatTabbedPaneUI
 
 		// increase size of repaint region to include part of content border
 		if( contentSeparatorHeight > 0 &&
-			getTabType() == TAB_TYPE_CARD &&
 			clientPropertyBoolean( tabPane, TABBED_PANE_SHOW_CONTENT_SEPARATOR, true ) )
 		{
 			int sh = scale( contentSeparatorHeight );
@@ -1205,7 +1212,9 @@ public class FlatTabbedPaneUI
 	}
 
 	protected void paintTabSelection( Graphics g, int tabPlacement, int x, int y, int w, int h ) {
-		g.setColor( tabPane.isEnabled() ? underlineColor : disabledUnderlineColor );
+		g.setColor( tabPane.isEnabled()
+			? (isTabbedPaneOrChildFocused() ? underlineColor : inactiveUnderlineColor)
+			: disabledUnderlineColor );
 
 		// paint underline selection
 		boolean atBottom = (getTabType() != TAB_TYPE_CARD);
@@ -1236,6 +1245,23 @@ public class FlatTabbedPaneUI
 		}
 	}
 
+	/** @since 2.2 */
+	@SuppressWarnings( "unchecked" )
+	protected boolean isTabbedPaneOrChildFocused() {
+		KeyboardFocusManager keyboardFocusManager = KeyboardFocusManager.getCurrentKeyboardFocusManager();
+
+		Object value = tabPane.getClientProperty( FlatClientProperties.COMPONENT_FOCUS_OWNER );
+		if( value instanceof Predicate ) {
+			return ((Predicate<JComponent>)value).test( tabPane ) &&
+				FlatUIUtils.isInActiveWindow( tabPane, keyboardFocusManager.getActiveWindow() );
+		}
+
+		Component focusOwner = keyboardFocusManager.getPermanentFocusOwner();
+		return focusOwner != null &&
+			SwingUtilities.isDescendingFrom( focusOwner, tabPane ) &&
+			FlatUIUtils.isInActiveWindow( focusOwner, keyboardFocusManager.getActiveWindow() );
+	}
+
 	/**
 	 * Actually does nearly the same as super.paintContentBorder() but
 	 *   - not using UIManager.getColor("TabbedPane.contentAreaColor") to be GUI builder friendly
@@ -3341,4 +3367,77 @@ public class FlatTabbedPaneUI
 				delegate.actionPerformed( e );
 		}
 	}
+
+	//---- class FlatSelectedTabRepainter -------------------------------------
+
+	private static class FlatSelectedTabRepainter
+		implements PropertyChangeListener//, Runnable
+	{
+		private static FlatSelectedTabRepainter instance;
+
+		private KeyboardFocusManager keyboardFocusManager;
+
+		static void install() {
+			synchronized( FlatSelectedTabRepainter.class ) {
+				if( instance != null )
+					return;
+
+				instance = new FlatSelectedTabRepainter();
+			}
+		}
+
+		FlatSelectedTabRepainter() {
+			keyboardFocusManager = KeyboardFocusManager.getCurrentKeyboardFocusManager();
+			keyboardFocusManager.addPropertyChangeListener( this );
+		}
+
+		private void uninstall() {
+			synchronized( FlatSelectedTabRepainter.class ) {
+				if( instance == null )
+					return;
+
+				keyboardFocusManager.removePropertyChangeListener( this );
+				keyboardFocusManager = null;
+				instance = null;
+			}
+		}
+
+		@Override
+		public void propertyChange( PropertyChangeEvent e ) {
+			// uninstall if no longer using FlatLaf
+			if( !(UIManager.getLookAndFeel() instanceof FlatLaf) ) {
+				uninstall();
+				return;
+			}
+
+			switch( e.getPropertyName() ) {
+				case "permanentFocusOwner":
+					Object oldValue = e.getOldValue();
+					Object newValue = e.getNewValue();
+					if( oldValue instanceof Component )
+						repaintSelectedTabs( (Component) oldValue );
+					if( newValue instanceof Component )
+						repaintSelectedTabs( (Component) newValue );
+					break;
+
+				case "activeWindow":
+					repaintSelectedTabs( keyboardFocusManager.getPermanentFocusOwner() );
+					break;
+			}
+		}
+
+		private void repaintSelectedTabs( Component c ) {
+			if( c instanceof JTabbedPane )
+				repaintSelectedTab( (JTabbedPane) c );
+
+			while( (c = SwingUtilities.getAncestorOfClass( JTabbedPane.class, c )) != null )
+				repaintSelectedTab( (JTabbedPane) c );
+		}
+
+		private void repaintSelectedTab( JTabbedPane tabbedPane ) {
+			TabbedPaneUI ui = tabbedPane.getUI();
+			if( ui instanceof FlatTabbedPaneUI )
+				((FlatTabbedPaneUI) ui).repaintTab( tabbedPane.getSelectedIndex() );
+		}
+	}
 }

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

@@ -245,7 +245,7 @@ public class FlatUIUtils
 			isInActiveWindow( c, keyboardFocusManager.getActiveWindow() );
 	}
 
-	private static boolean isInActiveWindow( Component c, Window activeWindow ) {
+	static boolean isInActiveWindow( Component c, Window activeWindow ) {
 		Window window = SwingUtilities.windowForComponent( c );
 		return window == activeWindow ||
 			(window != null && window.getType() == Window.Type.POPUP && window.getOwner() == activeWindow);

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

@@ -306,6 +306,7 @@ SplitPaneDivider.draggingColor = $Component.borderColor
 #---- TabbedPane ----
 
 TabbedPane.underlineColor = @accentUnderlineColor
+TabbedPane.inactiveUnderlineColor = mix(@accentUnderlineColor,$TabbedPane.background,60%)
 TabbedPane.disabledUnderlineColor = lighten(@background,23%)
 TabbedPane.hoverColor = darken($TabbedPane.background,5%,derived noAutoInverse)
 TabbedPane.focusColor = mix(@selectionBackground,$TabbedPane.background,25%)

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

@@ -313,6 +313,7 @@ SplitPaneDivider.draggingColor = $Component.borderColor
 #---- TabbedPane ----
 
 TabbedPane.underlineColor = @accentUnderlineColor
+TabbedPane.inactiveUnderlineColor = mix(@accentUnderlineColor,$TabbedPane.background,50%)
 TabbedPane.disabledUnderlineColor = darken(@background,28%)
 TabbedPane.hoverColor = darken($TabbedPane.background,7%,derived)
 TabbedPane.focusColor = mix(@selectionBackground,$TabbedPane.background,10%)

flatlaf-core/src/main/resources/com/formdev/flatlaf/IntelliJTheme$ThemeLaf.properties

@@ -82,6 +82,13 @@ HelpButton.hoverBorderColor = null
 Slider.focusedColor = fade($Component.focusColor,40%,derived)
 
 
+#---- TabbedPane ----
+
+# colors from JBUI.CurrentTheme.DefaultTabs.inactiveUnderlineColor()
+[light]TabbedPane.inactiveUnderlineColor = #9ca7b8
+[dark]TabbedPane.inactiveUnderlineColor = #747a80
+
+
 #---- ToggleButton ----
 
 ToggleButton.startBackground = $ToggleButton.background

flatlaf-core/src/test/java/com/formdev/flatlaf/ui/TestFlatStyleableInfo.java

@@ -693,6 +693,7 @@ public class TestFlatStyleableInfo
 			"selectedBackground", Color.class,
 			"selectedForeground", Color.class,
 			"underlineColor", Color.class,
+			"inactiveUnderlineColor", Color.class,
 			"disabledUnderlineColor", Color.class,
 			"hoverColor", Color.class,
 			"focusColor", Color.class,

flatlaf-core/src/test/java/com/formdev/flatlaf/ui/TestFlatStyling.java

@@ -862,6 +862,7 @@ public class TestFlatStyling
 		ui.applyStyle( "selectedBackground: #fff" );
 		ui.applyStyle( "selectedForeground: #fff" );
 		ui.applyStyle( "underlineColor: #fff" );
+		ui.applyStyle( "inactiveUnderlineColor: #fff" );
 		ui.applyStyle( "disabledUnderlineColor: #fff" );
 		ui.applyStyle( "hoverColor: #fff" );
 		ui.applyStyle( "focusColor: #fff" );