ComboBox: use small border if used as table editor

CHANGELOG.md

@@ -1,6 +1,11 @@
 FlatLaf Change Log
 ==================
 
+## Unreleased
+
+- ComboBox: Use small border if used as table editor.
+
+
 ## 0.13
 
 - Added developer information to Maven POM for Maven Central publishing.

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

@@ -72,9 +72,10 @@ public class FlatBorder
 		try {
 			FlatUIUtils.setRenderingHints( g2 );
 
-			float focusWidth = getFocusWidth();
+			boolean isCellEditor = FlatUIUtils.isTableCellEditor( c );
+			float focusWidth = isCellEditor ? 0 : getFocusWidth();
 			float borderWidth = getBorderWidth( c );
-			float arc = getArc();
+			float arc = isCellEditor ? 0 : getArc();
 
 			if( isFocused( c ) ) {
 				g2.setColor( getFocusColor( c ) );
@@ -134,7 +135,8 @@ public class FlatBorder
 
 	@Override
 	public Insets getBorderInsets( Component c, Insets insets ) {
-		float ow = getFocusWidth() + getLineWidth();
+		boolean isCellEditor = FlatUIUtils.isTableCellEditor( c );
+		float ow = (isCellEditor ? 0 : getFocusWidth()) + getLineWidth();
 
 		insets = super.getBorderInsets( c, insets );
 		insets.top = Math.round( scale( (float) insets.top ) + ow );

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

@@ -17,6 +17,7 @@
 package com.formdev.flatlaf.ui;
 
 import java.awt.Color;
+import java.awt.Component;
 import java.awt.Container;
 import java.awt.Graphics;
 import java.awt.Graphics2D;
@@ -80,6 +81,10 @@ public class FlatUIUtils
 		return (c instanceof ColorUIResource) ? new Color( c.getRGB(), true ) : c;
 	}
 
+	public static boolean isTableCellEditor( Component c ) {
+		return c instanceof JComponent && Boolean.TRUE.equals( ((JComponent)c).getClientProperty( "JComboBox.isTableCellEditor" ) );
+	}
+
 	/**
 	 * Sets rendering hints used for painting.
 	 */