diff --git a/CHANGELOG.md b/CHANGELOG.md
index 9630999c..c1a656f4 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -6,6 +6,8 @@ FlatLaf Change Log
 - Made some fixes for right-to-left support in ComboBox, Slider and ToolTip.
   (issue #18)
 - Fixed Java 9 module descriptor (broken since 0.14).
+- Made `JButton`, `JCheckBox`, `JRadioButton`, `JToggleButton` and `JSlider`
+  non-opaque. (issue #20)
 
 
 ## 0.15
diff --git a/flatlaf-core/src/main/java/com/formdev/flatlaf/ui/FlatButtonUI.java b/flatlaf-core/src/main/java/com/formdev/flatlaf/ui/FlatButtonUI.java
index 51b8139d..3fb884d9 100644
--- a/flatlaf-core/src/main/java/com/formdev/flatlaf/ui/FlatButtonUI.java
+++ b/flatlaf-core/src/main/java/com/formdev/flatlaf/ui/FlatButtonUI.java
@@ -131,6 +131,7 @@ public class FlatButtonUI
 			defaults_initialized = true;
 		}
 
+		LookAndFeel.installProperty( b, "opaque", false );
 		LookAndFeel.installProperty( b, "iconTextGap", scale( iconTextGap ) );
 
 		MigLayoutVisualPadding.install( b, focusWidth );
@@ -169,15 +170,16 @@ public class FlatButtonUI
 
 	@Override
 	public void update( Graphics g, JComponent c ) {
-		if( isHelpButton( c ) ) {
+		// fill background if opaque to avoid garbage if user sets opaque to true
+		if( c.isOpaque() )
 			FlatUIUtils.paintParentBackground( g, c );
+
+		if( isHelpButton( c ) ) {
 			helpButtonIcon.paintIcon( c, g, 0, 0 );
 			return;
 		}
 
-		if( c.isOpaque() && isContentAreaFilled( c ) ) {
-			FlatUIUtils.paintParentBackground( g, c );
-
+		if( isContentAreaFilled( c ) ) {
 			Color background = getBackground( c );
 			if( background != null ) {
 				Graphics2D g2 = (Graphics2D) g.create();
diff --git a/flatlaf-core/src/main/java/com/formdev/flatlaf/ui/FlatRadioButtonUI.java b/flatlaf-core/src/main/java/com/formdev/flatlaf/ui/FlatRadioButtonUI.java
index 1eadf049..0edbdcab 100644
--- a/flatlaf-core/src/main/java/com/formdev/flatlaf/ui/FlatRadioButtonUI.java
+++ b/flatlaf-core/src/main/java/com/formdev/flatlaf/ui/FlatRadioButtonUI.java
@@ -66,6 +66,7 @@ public class FlatRadioButtonUI
 			defaults_initialized = true;
 		}
 
+		LookAndFeel.installProperty( b, "opaque", false );
 		LookAndFeel.installProperty( b, "iconTextGap", scale( iconTextGap ) );
 
 		MigLayoutVisualPadding.install( b, null );
diff --git a/flatlaf-core/src/main/java/com/formdev/flatlaf/ui/FlatSliderUI.java b/flatlaf-core/src/main/java/com/formdev/flatlaf/ui/FlatSliderUI.java
index c0945008..0fd3bd2e 100644
--- a/flatlaf-core/src/main/java/com/formdev/flatlaf/ui/FlatSliderUI.java
+++ b/flatlaf-core/src/main/java/com/formdev/flatlaf/ui/FlatSliderUI.java
@@ -25,6 +25,7 @@ import java.awt.geom.Path2D;
 import java.awt.geom.RoundRectangle2D;
 import javax.swing.JComponent;
 import javax.swing.JSlider;
+import javax.swing.LookAndFeel;
 import javax.swing.UIManager;
 import javax.swing.plaf.ComponentUI;
 import javax.swing.plaf.basic.BasicSliderUI;
@@ -96,6 +97,8 @@ public class FlatSliderUI
 	protected void installDefaults( JSlider slider ) {
 		super.installDefaults( slider );
 
+		LookAndFeel.installProperty( slider, "opaque", false );
+
 		trackWidth = UIManager.getInt( "Slider.trackWidth" );
 		thumbWidth = UIManager.getInt( "Slider.thumbWidth" );