slightly changed style of default Light and Dark themes and added IntelliJ and Darcula themes to keep the old style:

- changed focus width from 2 to 0
- changed colors of selected checkbox and radio button
- increased diameter of center circle in selected radio button

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

@@ -0,0 +1,36 @@
+/*
+ * 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;
+
+/**
+ * A Flat LaF that has a dark color scheme and looks like Darcula LaF.
+ *
+ * @author Karl Tauber
+ */
+public class FlatDarculaLaf
+	extends FlatDarkLaf
+{
+	@Override
+	public String getName() {
+		return "Flat Darcula";
+	}
+
+	@Override
+	public String getDescription() {
+		return "Flat Darcula Look and Feel";
+	}
+}

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

@@ -0,0 +1,36 @@
+/*
+ * 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;
+
+/**
+ * A Flat LaF that has a light color scheme and looks like IntelliJ LaF.
+ *
+ * @author Karl Tauber
+ */
+public class FlatIntelliJLaf
+	extends FlatLightLaf
+{
+	@Override
+	public String getName() {
+		return "Flat IntelliJ";
+	}
+
+	@Override
+	public String getDescription() {
+		return "Flat IntelliJ Look and Feel";
+	}
+}

flatlaf-core/src/main/java/com/formdev/flatlaf/icons/FlatRadioButtonIcon.java

@@ -17,15 +17,21 @@
 package com.formdev.flatlaf.icons;
 
 import java.awt.Graphics2D;
+import java.awt.geom.Ellipse2D;
+import com.formdev.flatlaf.ui.FlatUIUtils;
 
 /**
  * Icon for {@link javax.swing.JRadioButton}.
  *
+ * @uiDefault RadioButton.icon.centerDiameter			int
+ *
  * @author Karl Tauber
  */
 public class FlatRadioButtonIcon
 	extends FlatCheckBoxIcon
 {
+	protected final int centerDiameter = FlatUIUtils.getUIInt( "RadioButton.icon.centerDiameter", 8 );
+
 	@Override
 	protected void paintFocusBorder( Graphics2D g2 ) {
 		g2.fillOval( 0, 0, iconSize, iconSize );
@@ -43,6 +49,7 @@ public class FlatRadioButtonIcon
 
 	@Override
 	protected void paintCheckmark( Graphics2D g2 ) {
-		g2.fillOval( focusWidth + 5, focusWidth + 5, 5, 5 );
+		float xy = (iconSize - centerDiameter) / 2f;
+		g2.fill( new Ellipse2D.Float( xy, xy, centerDiameter, centerDiameter ) );
 	}
 }

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

@@ -0,0 +1,28 @@
+#
+# 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.
+#
+
+# Colors and style mostly based on Darcula theme from IntelliJ IDEA Community Edition,
+# which is licensed under the Apache 2.0 license. Copyright 2000-2019 JetBrains s.r.o.
+# See: https://github.com/JetBrains/intellij-community/
+
+#---- Component ----
+
+Component.focusWidth=2
+
+
+#---- RadioButton ----
+
+RadioButton.icon.centerDiameter=5

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

@@ -0,0 +1,35 @@
+#
+# 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.
+#
+
+# Colors and style mostly based on IntelliJ theme from IntelliJ IDEA Community Edition,
+# which is licensed under the Apache 2.0 license. Copyright 2000-2019 JetBrains s.r.o.
+# See: https://github.com/JetBrains/intellij-community/
+
+#---- CheckBox ----
+
+CheckBox.icon.selectedBorderColor=4982CC
+CheckBox.icon.selectedBackground=4D89C9
+CheckBox.icon.checkmarkColor=FFFFFF
+
+
+#---- Component ----
+
+Component.focusWidth=2
+
+
+#---- RadioButton ----
+
+RadioButton.icon.centerDiameter=5

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

@@ -93,7 +93,7 @@ ComboBox.padding=1,6,1,6
 
 #---- Component ----
 
-Component.focusWidth=2
+Component.focusWidth=0
 Component.arc=5
 
 
@@ -189,6 +189,7 @@ ProgressBar.verticalSize=6,146
 
 RadioButton.border=com.formdev.flatlaf.ui.FlatMarginBorder
 RadioButton.icon=com.formdev.flatlaf.icons.FlatRadioButtonIcon
+RadioButton.icon.centerDiameter=8
 
 
 #---- RadioButtonMenuItem ----

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

@@ -82,13 +82,13 @@ Button.toolbar.pressedBackground=cfcfcf
 
 CheckBox.icon.borderColor=878787
 CheckBox.icon.disabledBorderColor=BDBDBD
-CheckBox.icon.selectedBorderColor=4982CC
+CheckBox.icon.selectedBorderColor=878787
 CheckBox.icon.focusedBorderColor=7B9FC7
 CheckBox.icon.selectedFocusedBorderColor=ACCFF7
 CheckBox.icon.background=FFFFFF
 CheckBox.icon.disabledBackground=@background
-CheckBox.icon.selectedBackground=4D89C9
+CheckBox.icon.selectedBackground=FFFFFF
-CheckBox.icon.checkmarkColor=FFFFFF
+CheckBox.icon.checkmarkColor=4D89C9
 CheckBox.icon.disabledCheckmarkColor=ABABAB
 
 

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

@@ -44,6 +44,8 @@ class ControlBar
 		DefaultComboBoxModel<LafInfo> lafModel = new DefaultComboBoxModel<>();
 		lafModel.addElement( new LafInfo( "Flat Light (F1)", FlatLightLaf.class.getName() ) );
 		lafModel.addElement( new LafInfo( "Flat Dark (F2)", FlatDarkLaf.class.getName() ) );
+		lafModel.addElement( new LafInfo( "Flat IntelliJ (F3)", FlatIntelliJLaf.class.getName() ) );
+		lafModel.addElement( new LafInfo( "Flat Darcula (F4)", FlatDarculaLaf.class.getName() ) );
 
 		UIManager.LookAndFeelInfo[] lookAndFeels = UIManager.getInstalledLookAndFeels();
 		for( UIManager.LookAndFeelInfo lookAndFeel : lookAndFeels ) {
@@ -82,6 +84,8 @@ class ControlBar
 		// register F1, F2, ... keys to switch to Light, Dark or other LaFs
 		registerSwitchToLookAndFeel( KeyEvent.VK_F1, FlatLightLaf.class.getName() );
 		registerSwitchToLookAndFeel( KeyEvent.VK_F2, FlatDarkLaf.class.getName() );
+		registerSwitchToLookAndFeel( KeyEvent.VK_F3, FlatIntelliJLaf.class.getName() );
+		registerSwitchToLookAndFeel( KeyEvent.VK_F4, FlatDarculaLaf.class.getName() );
 
 		registerSwitchToLookAndFeel( KeyEvent.VK_F10, NimbusLookAndFeel.class.getName() );
 		registerSwitchToLookAndFeel( KeyEvent.VK_F11, MetalLookAndFeel.class.getName() );