added developer information to Maven POM for Maven Central publishing

The Swing fonts are not updated when the user changes system font size (System Settings > Fonts > Force Font DPI). A application restart is necessary. This is the same behavior as in native KDE applications.

tested on Kubuntu 19.04

CHANGELOG.md

@@ -1,6 +1,21 @@
 FlatLaf Change Log
 ==================
 
+## 0.13
+
+- Added developer information to Maven POM for Maven Central publishing.
+
+
+## 0.12
+
+- Support Linux. (issue #2)
+- Added `Flat*Laf.install()` methods.
+- macOS: Use native screen menu bar if system property
+  `apple.laf.useScreenMenuBar` is `true`.
+- Windows: Update fonts (and scaling) when user changes Windows text size
+  (Settings > Ease of Access > Display > Make text bigger).
+
+
 ## 0.11
 
 - Changed Maven groupId to `com.formdev` and artifactId to `flatlaf`.

README.md

@@ -19,26 +19,22 @@ IntelliJ IDEA 2019.2+ and uses mostly the same colors and icons.
 Demo
 ----
 
-Download
+[![Download Demo](https://download.formdev.com/flatlaf/images/download-demo.svg)](https://download.formdev.com/flatlaf/flatlaf-demo-latest.jar)
-[flatlaf-demo-0.11.jar](https://download.formdev.com/flatlaf/flatlaf-demo-0.11.jar)
+
-and run it with `java -jar flatlaf-demo-0.11.jar` (or double-click it). Requires
+Run demo with `java -jar flatlaf-demo-<version>.jar` (or double-click it).
-Java 8 or newer.
+Requires Java 8 or newer.
 
 
 Download
 --------
 
-[ ![Download](https://api.bintray.com/packages/jformdesigner/flatlaf/flatlaf/images/download.svg) ](https://bintray.com/jformdesigner/flatlaf/flatlaf/_latestVersion)
+[![Download](https://api.bintray.com/packages/jformdesigner/flatlaf/flatlaf/images/download.svg)](https://bintray.com/jformdesigner/flatlaf/flatlaf/_latestVersion)
 
-For Maven or Gradle use:
+Download from JCenter and Maven Central is coming soon.
-
-    Repository:   jcenter (https://jcenter.bintray.com/) 
-    Group Id:     com.formdev
-    Artifact Id:  flatlaf
-    Version:      0.11
 
 
-License
+Documentation
--------
+-------------
 
-FlatLaf is open source licensed under the [Apache 2.0 License](LICENSE)
+For more information and documentation visit
+[FlatLaf Home](https://www.formdev.com/flatlaf/)

build.gradle.kts

@@ -14,7 +14,7 @@
  * limitations under the License.
  */
 
-version = "0.11"
+version = "0.13"
 
 // check required Java version
 if( JavaVersion.current() < JavaVersion.VERSION_1_8 )

flatlaf-core/build.gradle.kts

@@ -117,6 +117,14 @@ publishing {
 					}
 				}
 
+				developers {
+					developer {
+						name.set( "Karl Tauber" )
+						organization.set( "FormDev Software GmbH" )
+						organizationUrl.set( "https://www.formdev.com/" )
+					}
+				}
+
 				scm {
 					url.set( "https://github.com/JFormDesigner/FlatLaf" )
 				}

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

@@ -24,6 +24,10 @@ package com.formdev.flatlaf;
 public class FlatDarculaLaf
 	extends FlatDarkLaf
 {
+	public static boolean install( ) {
+		return install( new FlatDarculaLaf() );
+	}
+
 	@Override
 	public String getName() {
 		return "Flat Darcula";

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

@@ -24,6 +24,10 @@ package com.formdev.flatlaf;
 public class FlatDarkLaf
 	extends FlatLaf
 {
+	public static boolean install( ) {
+		return install( new FlatDarkLaf() );
+	}
+
 	@Override
 	public String getName() {
 		return "Flat Dark";

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

@@ -24,6 +24,10 @@ package com.formdev.flatlaf;
 public class FlatIntelliJLaf
 	extends FlatLightLaf
 {
+	public static boolean install( ) {
+		return install( new FlatIntelliJLaf() );
+	}
+
 	@Override
 	public String getName() {
 		return "Flat IntelliJ";

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

@@ -21,6 +21,7 @@ import java.awt.Color;
 import java.awt.Component;
 import java.awt.Container;
 import java.awt.Dimension;
+import java.awt.EventQueue;
 import java.awt.Font;
 import java.awt.Insets;
 import java.awt.KeyboardFocusManager;
@@ -28,6 +29,8 @@ import java.awt.Toolkit;
 import java.awt.Window;
 import java.awt.event.AWTEventListener;
 import java.awt.event.KeyEvent;
+import java.beans.PropertyChangeEvent;
+import java.beans.PropertyChangeListener;
 import java.io.IOException;
 import java.io.InputStream;
 import java.util.ArrayList;
@@ -39,9 +42,11 @@ import java.util.function.Function;
 import javax.swing.AbstractButton;
 import javax.swing.JLabel;
 import javax.swing.JTabbedPane;
+import javax.swing.LookAndFeel;
 import javax.swing.SwingUtilities;
 import javax.swing.UIDefaults;
 import javax.swing.UIManager;
+import javax.swing.UnsupportedLookAndFeelException;
 import javax.swing.UIDefaults.LazyValue;
 import javax.swing.plaf.ColorUIResource;
 import javax.swing.plaf.DimensionUIResource;
@@ -70,9 +75,22 @@ public abstract class FlatLaf
 
 	private BasicLookAndFeel base;
 
+	private String desktopPropertyName;
+	private PropertyChangeListener desktopPropertyListener;
+
 	private AWTEventListener mnemonicListener;
 	private static boolean altKeyPressed;
 
+	public static boolean install( LookAndFeel newLookAndFeel ) {
+		try {
+		    UIManager.setLookAndFeel( newLookAndFeel );
+		    return true;
+		} catch( Exception ex ) {
+		    System.err.println( "Failed to initialize look and feel " + newLookAndFeel.getClass().getName() );
+		    return false;
+		}
+	}
+
 	@Override
 	public String getID() {
 		return getName();
@@ -100,10 +118,35 @@ public abstract class FlatLaf
 				altKeyChanged( e.getID() == KeyEvent.KEY_PRESSED );
 		};
 		Toolkit.getDefaultToolkit().addAWTEventListener( mnemonicListener, AWTEvent.KEY_EVENT_MASK );
+
+		// listen to desktop property changes to update UI if system font or scaling changes
+		if( SystemInfo.IS_WINDOWS ) {
+			// Windows 10 allows increasing font size independent of scaling:
+			//   Settings > Ease of Access > Display > Make text bigger (100% - 225%)
+			desktopPropertyName = "win.messagebox.font";
+		} else if( SystemInfo.IS_LINUX ) {
+			// Linux/Gnome allows extra scaling and larger text:
+			//   Settings > Devices > Displays > Scale (100% or 200%)
+			//   Settings > Universal access > Large Text (off or on, 125%)
+			desktopPropertyName = "gnome.Xft/DPI";
+		}
+		if( desktopPropertyName != null ) {
+			desktopPropertyListener = e -> {
+				reSetLookAndFeel();
+			};
+			Toolkit.getDefaultToolkit().addPropertyChangeListener( desktopPropertyName, desktopPropertyListener );
+		}
 	}
 
 	@Override
 	public void uninitialize() {
+		// remove desktop property listener
+		if( desktopPropertyListener != null ) {
+			Toolkit.getDefaultToolkit().removePropertyChangeListener( desktopPropertyName, desktopPropertyListener );
+			desktopPropertyName = null;
+			desktopPropertyListener = null;
+		}
+
 		// remove mnemonic listener
 		if( mnemonicListener != null ) {
 			Toolkit.getDefaultToolkit().removeAWTEventListener( mnemonicListener );
@@ -157,9 +200,17 @@ public abstract class FlatLaf
 		defaults.put( "Spinner.disabledBackground", control );
 		defaults.put( "Spinner.disabledForeground", control );
 
+		// remember MenuBarUI from Mac Aqua LaF if Mac screen menubar is enabled
+		boolean useScreenMenuBar = SystemInfo.IS_MAC && "true".equals( System.getProperty( "apple.laf.useScreenMenuBar" ) );
+		Object aquaMenuBarUI = useScreenMenuBar ? defaults.get( "MenuBarUI" ) : null;
+
 		initFonts( defaults );
 		loadDefaultsFromProperties( defaults );
 
+		// use Aqua MenuBarUI if Mac screen menubar is enabled
+		if( useScreenMenuBar )
+			defaults.put( "MenuBarUI", aquaMenuBarUI );
+
 		return defaults;
 	}
 
@@ -182,7 +233,8 @@ public abstract class FlatLaf
 			uiFont = (font instanceof FontUIResource) ? (FontUIResource) font : new FontUIResource( font );
 
 		} else if( SystemInfo.IS_LINUX ) {
-			System.err.println( "WARNING: FlatLaf is not yet tested on Linux!" );
+			Font font = LinuxFontPolicy.getFont();
+			uiFont = (font instanceof FontUIResource) ? (FontUIResource) font : new FontUIResource( font );
 		}
 
 		if( uiFont == null )
@@ -458,6 +510,35 @@ public abstract class FlatLaf
 		return strs;
 	}
 
+	private static void reSetLookAndFeel() {
+		EventQueue.invokeLater( () -> {
+			try {
+				// re-set current LaF
+				LookAndFeel lookAndFeel = UIManager.getLookAndFeel();
+				UIManager.setLookAndFeel( lookAndFeel );
+
+				// must fire property change events ourself because old and new LaF are the same
+				PropertyChangeEvent e = new PropertyChangeEvent( UIManager.class, "lookAndFeel", lookAndFeel, lookAndFeel );
+				for( PropertyChangeListener l : UIManager.getPropertyChangeListeners() )
+					l.propertyChange( e );
+
+				// update UI
+				updateUI();
+			} catch( UnsupportedLookAndFeelException ex ) {
+				ex.printStackTrace();
+			}
+		} );
+	}
+
+	/**
+	 * Update UI of all application windows.
+	 * Invoke after changing LaF.
+	 */
+	public static void updateUI() {
+		for( Window w : Window.getWindows() )
+			SwingUtilities.updateComponentTreeUI( w );
+	}
+
 	public static boolean isShowMnemonics() {
 		return altKeyPressed || !UIManager.getBoolean( "Component.hideMnemonics" );
 	}

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

@@ -24,6 +24,10 @@ package com.formdev.flatlaf;
 public class FlatLightLaf
 	extends FlatLaf
 {
+	public static boolean install( ) {
+		return install( new FlatLightLaf() );
+	}
+
 	@Override
 	public String getName() {
 		return "Flat Light";

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

@@ -0,0 +1,248 @@
+/*
+ * Copyright 2019 FormDev Software GmbH
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+package com.formdev.flatlaf;
+
+import java.awt.Font;
+import java.awt.GraphicsEnvironment;
+import java.awt.Toolkit;
+import java.io.BufferedReader;
+import java.io.File;
+import java.io.FileReader;
+import java.io.IOException;
+import java.util.ArrayList;
+import java.util.Collections;
+import java.util.List;
+import java.util.StringTokenizer;
+import javax.swing.text.StyleContext;
+import com.formdev.flatlaf.util.SystemInfo;
+
+/**
+ * @author Karl Tauber
+ */
+class LinuxFontPolicy
+{
+	static Font getFont() {
+		return SystemInfo.IS_KDE ? getKDEFont() : getGnomeFont();
+	}
+
+	/**
+	 * Gets the default font for Gnome.
+	 */
+	private static Font getGnomeFont() {
+		// see class com.sun.java.swing.plaf.gtk.PangoFonts background information
+
+		Object fontName = Toolkit.getDefaultToolkit().getDesktopProperty( "gnome.Gtk/FontName" );
+		if( !(fontName instanceof String) )
+			fontName = "sans 10";
+
+		String family = "";
+		int style = Font.PLAIN;
+		int size = 10;
+
+		StringTokenizer st = new StringTokenizer( (String) fontName );
+		while( st.hasMoreTokens() ) {
+			String word = st.nextToken();
+
+			if( word.equalsIgnoreCase( "italic" ) )
+				style |= Font.ITALIC;
+			else if( word.equalsIgnoreCase( "bold" ) )
+				style |= Font.BOLD;
+			else if( Character.isDigit( word.charAt( 0 ) ) ) {
+				try {
+					size = Integer.parseInt( word );
+				} catch( NumberFormatException ex ) {
+					// ignore
+				}
+			} else
+				family = family.isEmpty() ? word : (family + ' ' + word);
+		}
+
+		// scale font size
+		double dsize = size * getGnomeFontScale();
+		size = (int) (dsize + 0.5);
+		if( size < 1 )
+			size = 1;
+
+		// handle logical font names
+		String logicalFamily = mapFcName( family.toLowerCase() );
+		if( logicalFamily != null )
+			family = logicalFamily;
+
+		return createFont( family, style, size, dsize );
+	}
+
+	private static Font createFont( String family, int style, int size, double dsize ) {
+		// using StyleContext.getFont() here because it uses
+		// sun.font.FontUtilities.getCompositeFontUIResource()
+		Font font = new StyleContext().getFont( family, style, size );
+
+		// set font size in floating points
+		font = font.deriveFont( style, (float) dsize );
+
+		return font;
+	}
+
+	private static double getGnomeFontScale() {
+		// see class com.sun.java.swing.plaf.gtk.PangoFonts background information
+
+		Object value = Toolkit.getDefaultToolkit().getDesktopProperty( "gnome.Xft/DPI" );
+		if( value instanceof Integer ) {
+			int dpi = ((Integer)value).intValue() / 1024;
+			if( dpi == -1 )
+				dpi = 96;
+			if( dpi < 50 )
+				dpi = 50;
+			return dpi / 72.0;
+		} else {
+			return GraphicsEnvironment.getLocalGraphicsEnvironment()
+				.getDefaultScreenDevice().getDefaultConfiguration()
+				.getNormalizingTransform().getScaleY();
+		}
+	}
+
+	/**
+	 * map GTK/fontconfig names to equivalent JDK logical font name
+	 */
+	private static String mapFcName( String name ) {
+		switch( name ) {
+			case "sans":		return "sansserif";
+			case "sans-serif":	return "sansserif";
+			case "serif":		return "serif";
+			case "monospace":	return "monospaced";
+		}
+		return null;
+	}
+
+	/**
+	 * Gets the default font for KDE for KDE configuration files.
+	 *
+	 * The Swing fonts are not updated when the user changes system font size
+	 * (System Settings > Fonts > Force Font DPI). A application restart is necessary.
+	 * This is the same behavior as in native KDE applications.
+	 *
+	 * The "display scale factor" (kdeglobals: [KScreen] > ScaleFactor) is not used
+	 * KDE also does not use it to calculate font size. Only forceFontDPI is used by KDE.
+	 * If user changes "display scale factor" (System Settings > Display and Monitors >
+	 * Displays > Scale Display), the forceFontDPI is also changed to reflect the scale factor.
+	 */
+	private static Font getKDEFont() {
+		List<String> kdeglobals = readConfig( "kdeglobals" );
+		List<String> kcmfonts = readConfig( "kcmfonts" );
+
+		String generalFont = getConfigEntry( kdeglobals, "General", "font" );
+		String forceFontDPI = getConfigEntry( kcmfonts, "General", "forceFontDPI" );
+
+		String family = "sansserif";
+		int style = Font.PLAIN;
+		int size = 10;
+
+		if( generalFont != null ) {
+			List<String> strs = FlatLaf.split( generalFont, ',' );
+			try {
+				family = strs.get( 0 );
+				size = Integer.parseInt( strs.get( 1 ) );
+				if( "75".equals( strs.get( 4 ) ) )
+					style |= Font.BOLD;
+				if( "1".equals( strs.get( 5 ) ) )
+					style |= Font.ITALIC;
+			} catch( RuntimeException ex ) {
+				ex.printStackTrace();
+			}
+		}
+
+		// font dpi
+		int dpi = 96;
+		if( forceFontDPI != null ) {
+			try {
+				dpi = Integer.parseInt( forceFontDPI );
+				if( dpi <= 0 )
+					dpi = 96;
+				if( dpi < 50 )
+					dpi = 50;
+			} catch( NumberFormatException ex ) {
+				ex.printStackTrace();
+			}
+		}
+
+		// scale font size
+		double fontScale = dpi / 72.0;
+		double dsize = size * fontScale;
+		size = (int) (dsize + 0.5);
+		if( size < 1 )
+			size = 1;
+
+		return createFont( family, style, size, dsize );
+	}
+
+	private static List<String> readConfig( String filename ) {
+		File userHome = new File( System.getProperty( "user.home" ) );
+
+		// search for config file
+		String[] configDirs = {
+			".config", // KDE 5
+			".kde4/share/config", // KDE 4
+			".kde/share/config"// KDE 3
+		};
+		File file = null;
+		for( String configDir : configDirs ) {
+			file = new File( userHome, configDir + "/" + filename );
+			if( file.isFile() )
+				break;
+		}
+		if( !file.isFile() )
+			return Collections.emptyList();
+
+		// read config file
+		ArrayList<String> lines = new ArrayList<>( 200 );
+		try( BufferedReader reader = new BufferedReader( new FileReader( file ) ) ) {
+			String line = null;
+			while( (line = reader.readLine()) != null )
+				lines.add( line );
+		} catch( IOException ex ) {
+			ex.printStackTrace();
+		}
+		return lines;
+	}
+
+	private static String getConfigEntry( List<String> config, String group, String key ) {
+		int groupLength = group.length();
+		int keyLength = key.length();
+		boolean inGroup = false;
+		for( String line : config ) {
+			if( !inGroup ) {
+				if( line.length() >= groupLength + 2 &&
+					line.charAt( 0 ) == '[' &&
+					line.charAt( groupLength + 1 ) == ']' &&
+					line.indexOf( group ) == 1 )
+				{
+					inGroup = true;
+				}
+			} else {
+				if( line.startsWith( "[" ) )
+					return null;
+
+				if( line.length() >= keyLength + 2 &&
+					line.charAt( keyLength ) == '=' &&
+					line.startsWith( key ) )
+				{
+					return line.substring( keyLength + 1 );
+				}
+			}
+		}
+		return null;
+	}
+}

flatlaf-core/src/main/java/com/formdev/flatlaf/util/SystemInfo.java

@@ -40,6 +40,9 @@ public class SystemInfo
 	// Java VMs
 	public static final boolean IS_JETBRAINS_JVM;
 
+	// UI toolkits
+	public static final boolean IS_KDE;
+
 	static {
 		// platforms
 		String osName = System.getProperty( "os.name" ).toLowerCase( Locale.ENGLISH );
@@ -58,6 +61,9 @@ public class SystemInfo
 		// Java VMs
 		IS_JETBRAINS_JVM = System.getProperty( "java.vm.vendor", "Unknown" )
 			.toLowerCase( Locale.ENGLISH ).contains( "jetbrains" );
+
+		// UI toolkits
+		IS_KDE = (IS_LINUX && System.getenv( "KDE_FULL_SESSION" ) != null);
 	}
 
 	private static long scanVersion( String version ) {

flatlaf-core/src/main/java/com/formdev/flatlaf/util/UIScale.java

@@ -48,8 +48,7 @@ import javax.swing.plaf.UIResource;
  *
  * 2) user scaling mode
  *
- * This mode is for Java 8 compatibility and can be removed when changing minimum
+ * This mode is mainly for Java 8 compatibility, but is also used on Linux.
- * required Java version to 9.
  * The user scale factor is computed based on the used font.
  * The JRE does not scale anything.
  * So we have to invoke {@link #scale(float)} where necessary.
@@ -66,7 +65,7 @@ public class UIScale
 
 	private static Boolean jreHiDPI;
 
-	public static boolean isJreHiDPIEnabled() {
+	public static boolean isSystemScalingEnabled() {
 		if( jreHiDPI != null )
 			return jreHiDPI;
 
@@ -94,11 +93,11 @@ public class UIScale
 	}
 
 	public static double getSystemScaleFactor( Graphics2D g ) {
-		return isJreHiDPIEnabled() ? g.getDeviceConfiguration().getDefaultTransform().getScaleX() : 1;
+		return isSystemScalingEnabled() ? g.getDeviceConfiguration().getDefaultTransform().getScaleX() : 1;
 	}
 
 	public static double getSystemScaleFactor( GraphicsConfiguration gc ) {
-		return isJreHiDPIEnabled() ? gc.getDefaultTransform().getScaleX() : 1;
+		return isSystemScalingEnabled() ? gc.getDefaultTransform().getScaleX() : 1;
 	}
 
 	//---- user scaling (Java 8) ----------------------------------------------
@@ -111,7 +110,7 @@ public class UIScale
 			return;
 		initialized = true;
 
-		if( isEnabled() ) {
+		if( isUserScalingEnabled() ) {
 			// listener to update scale factor if LaF changed or if Label.font changed
 			// (e.g. option "Override default fonts" in IntelliJ IDEA)
 			PropertyChangeListener listener = new PropertyChangeListener() {
@@ -135,7 +134,7 @@ public class UIScale
 	}
 
 	private static void updateScaleFactor() {
-		if( !isEnabled() )
+		if( !isUserScalingEnabled() )
 			return;
 
 		// use font size to calculate scale factor (instead of DPI)
@@ -158,15 +157,15 @@ public class UIScale
 			if( "Tahoma".equals( font.getFamily() ) )
 				fontSizeDivider = 11f;
 		} else if( SystemInfo.IS_LINUX ) {
-			// default font size for Unity and Gnome is 15
+			// default font size for Unity and Gnome is 15 and for KDE it is 13
-			fontSizeDivider = 15f;
+			fontSizeDivider = SystemInfo.IS_KDE ? 13f : 15f;
 		}
 
 		return font.getSize() / fontSizeDivider;
 	}
 
-	private static boolean isEnabled() {
+	private static boolean isUserScalingEnabled() {
-		if( isJreHiDPIEnabled() )
+		if( isSystemScalingEnabled() && !SystemInfo.IS_LINUX )
 			return false; // disable user scaling if JRE scales
 
 		// same as in IntelliJ IDEA
@@ -179,7 +178,7 @@ public class UIScale
 	 * or "sun.java2d.uiScale" to the given font.
 	 */
 	public static FontUIResource applyCustomScaleFactor( FontUIResource font ) {
-		if( UIScale.isJreHiDPIEnabled() )
+		if( UIScale.isSystemScalingEnabled() )
 			return font;
 
 		String uiScale = System.getProperty( "flatlaf.uiScale" );

flatlaf-core/src/test/java/com/formdev/flatlaf/FlatInspector.java

@@ -23,6 +23,7 @@ import java.awt.Dimension;
 import java.awt.EventQueue;
 import java.awt.Font;
 import java.awt.Graphics;
+import java.awt.Graphics2D;
 import java.awt.Insets;
 import java.awt.Rectangle;
 import java.awt.event.MouseEvent;
@@ -41,6 +42,7 @@ import javax.swing.border.LineBorder;
 import javax.swing.plaf.UIResource;
 import javax.swing.text.JTextComponent;
 import com.formdev.flatlaf.ui.FlatToolTipUI;
+import com.formdev.flatlaf.ui.FlatUIUtils;
 import com.formdev.flatlaf.util.UIScale;
 
 /**
@@ -103,7 +105,7 @@ public class FlatInspector
 	private void inspect( int x, int y ) {
 		Container contentPane = rootPane.getContentPane();
 		Component c = SwingUtilities.getDeepestComponentAt( contentPane, x, y );
-		if( c == contentPane || c.getParent() == contentPane )
+		if( c == contentPane || (c != null && c.getParent() == contentPane) )
 			c = null;
 
 		if( c == lastComponent )
@@ -137,6 +139,12 @@ public class FlatInspector
 				g.setColor( getBackground() );
 				g.fillRect( 0, 0, getWidth(), getHeight() );
 			}
+
+			@Override
+			protected void paintBorder( Graphics g ) {
+				FlatUIUtils.setRenderingHints( (Graphics2D) g );
+				super.paintBorder( g );
+			}
 		};
 		c.setBackground( new Color( 255, 0, 0, 32 ) );
 		c.setBorder( new LineBorder( Color.red ) );

flatlaf-core/src/test/java/com/formdev/flatlaf/FlatTestFrame.java

@@ -22,6 +22,8 @@ import java.awt.event.ComponentEvent;
 import java.awt.event.KeyEvent;
 import java.awt.event.WindowAdapter;
 import java.awt.event.WindowEvent;
+import java.beans.PropertyChangeEvent;
+import java.beans.PropertyChangeListener;
 import java.util.prefs.Preferences;
 import javax.swing.*;
 import javax.swing.plaf.ColorUIResource;
@@ -68,11 +70,7 @@ public class FlatTestFrame
 			ex.printStackTrace();
 
 			// fallback
-			try {
+			FlatLightLaf.install();
-				UIManager.setLookAndFeel( new FlatLightLaf() );
-			} catch( Exception ex2 ) {
-				ex2.printStackTrace();
-			}
 		}
 
 		// create frame
@@ -101,7 +99,8 @@ public class FlatTestFrame
 			  continue;
 
 			if( (SystemInfo.IS_WINDOWS && className.equals( "com.sun.java.swing.plaf.windows.WindowsLookAndFeel" )) ||
-				(SystemInfo.IS_MAC && className.equals( "com.apple.laf.AquaLookAndFeel") ) )
+				(SystemInfo.IS_MAC && className.equals( "com.apple.laf.AquaLookAndFeel") ) ||
+				(SystemInfo.IS_LINUX && className.equals( "com.sun.java.swing.plaf.gtk.GTKLookAndFeel") ) )
 				name += " (F9)";
 			else if( className.equals( MetalLookAndFeel.class.getName() ) )
 				name += " (F10)";
@@ -139,6 +138,8 @@ public class FlatTestFrame
 			registerSwitchToLookAndFeel( KeyEvent.VK_F9, "com.sun.java.swing.plaf.windows.WindowsLookAndFeel" );
 		else if( SystemInfo.IS_MAC )
 			registerSwitchToLookAndFeel( KeyEvent.VK_F9, "com.apple.laf.AquaLookAndFeel" );
+		else if( SystemInfo.IS_LINUX )
+			registerSwitchToLookAndFeel( KeyEvent.VK_F9, "com.sun.java.swing.plaf.gtk.GTKLookAndFeel" );
 		registerSwitchToLookAndFeel( KeyEvent.VK_F10, MetalLookAndFeel.class.getName() );
 		registerSwitchToLookAndFeel( KeyEvent.VK_F11, NimbusLookAndFeel.class.getName() );
 
@@ -168,6 +169,18 @@ public class FlatTestFrame
 				updateTitle();
 			}
 		} );
+
+		UIManager.addPropertyChangeListener( e -> {
+			if( "lookAndFeel".equals( e.getPropertyName() ) ) {
+				EventQueue.invokeLater( () -> {
+					// update title because user scale factor may change
+					updateTitle();
+
+					// enable/disable scale factor combobox
+					updateScaleFactorComboBox();
+				} );
+			}
+		} );
 	}
 
 	private void updateTitle() {
@@ -234,14 +247,8 @@ public class FlatTestFrame
 				// change look and feel
 				UIManager.setLookAndFeel( lafClassName );
 
-				// update title because user scale factor may change
-				updateTitle();
-
-				// enable/disable scale factor combobox
-				updateScaleFactorComboBox();
-
 				// update all components
-				SwingUtilities.updateComponentTreeUI( this );
+				FlatLaf.updateUI();
 
 				// increase size of frame if necessary
 				if( pack )
@@ -394,7 +401,7 @@ public class FlatTestFrame
 	}
 
 	private void updateScaleFactorComboBox() {
-		scaleFactorComboBox.setEnabled( !UIScale.isJreHiDPIEnabled() && UIManager.getLookAndFeel() instanceof FlatLaf );
+		scaleFactorComboBox.setEnabled( !UIScale.isSystemScalingEnabled() && UIManager.getLookAndFeel() instanceof FlatLaf );
 	}
 
 	private void initComponents() {

flatlaf-demo/src/main/java/com/formdev/flatlaf/demo/ControlBar.java

@@ -58,7 +58,8 @@ class ControlBar
 			  continue;
 
 			if( (SystemInfo.IS_WINDOWS && className.equals( "com.sun.java.swing.plaf.windows.WindowsLookAndFeel" )) ||
-				(SystemInfo.IS_MAC && className.equals( "com.apple.laf.AquaLookAndFeel") ) )
+				(SystemInfo.IS_MAC && className.equals( "com.apple.laf.AquaLookAndFeel") ) ||
+				(SystemInfo.IS_LINUX && className.equals( "com.sun.java.swing.plaf.gtk.GTKLookAndFeel") ) )
 				name += " (F9)";
 			else if( className.equals( MetalLookAndFeel.class.getName() ) )
 				name += " (F10)";
@@ -78,6 +79,15 @@ class ControlBar
 		lafModel.setSelectedItem( lafModel.getElementAt( sel ) );
 
 		lookAndFeelComboBox.setModel( lafModel );
+
+		UIManager.addPropertyChangeListener( e -> {
+			if( "lookAndFeel".equals( e.getPropertyName() ) ) {
+				EventQueue.invokeLater( () -> {
+					// update info label because user scale factor may change
+					updateInfoLabel();
+				} );
+			}
+		} );
 	}
 
 	void initialize( JFrame frame, JTabbedPane tabbedPane ) {
@@ -94,6 +104,8 @@ class ControlBar
 			registerSwitchToLookAndFeel( KeyEvent.VK_F9, "com.sun.java.swing.plaf.windows.WindowsLookAndFeel" );
 		else if( SystemInfo.IS_MAC )
 			registerSwitchToLookAndFeel( KeyEvent.VK_F9, "com.apple.laf.AquaLookAndFeel" );
+		else if( SystemInfo.IS_LINUX )
+			registerSwitchToLookAndFeel( KeyEvent.VK_F9, "com.sun.java.swing.plaf.gtk.GTKLookAndFeel" );
 		registerSwitchToLookAndFeel( KeyEvent.VK_F10, MetalLookAndFeel.class.getName() );
 		registerSwitchToLookAndFeel( KeyEvent.VK_F11, NimbusLookAndFeel.class.getName() );
 
@@ -170,11 +182,8 @@ class ControlBar
 				// change look and feel
 				UIManager.setLookAndFeel( newLaf.className );
 
-				// update info label because user scale factor may change
-				updateInfoLabel();
-
 				// update all components
-				SwingUtilities.updateComponentTreeUI( frame );
+				FlatLaf.updateUI();
 
 				// increase size of frame if necessary
 				int width = frame.getWidth();

flatlaf-demo/src/main/java/com/formdev/flatlaf/demo/FlatLafDemo.java

@@ -46,11 +46,7 @@ public class FlatLafDemo
 			ex.printStackTrace();
 
 			// fallback
-			try {
+			FlatLightLaf.install();
-				UIManager.setLookAndFeel( new FlatLightLaf() );
-			} catch( Exception ex2 ) {
-				ex2.printStackTrace();
-			}
 		}
 
 		// create frame