Button: make button square if button text is "..." or a single character

CHANGELOG.md

@@ -10,6 +10,7 @@ FlatLaf Change Log
   check whether the current look and feel is FlatLaf.
 - Fixed selection background of checkbox in table cell.
 - Fixed jittery submenu rendering on Mac. (issue #10)
+- Button: Make button square if button text is "..." or a single character.
 - ComboBox: Fixed issues with NetBeans `org.openide.awt.ColorComboBox`
   component.
 - Hex color values in `.properties` files now must start with a `#` character.

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

@@ -163,10 +163,13 @@ public class FlatButtonUI
 	}
 
 	static boolean isIconOnlyButton( Component c ) {
-		String text;
-		return c instanceof JButton &&
-			((JButton)c).getIcon() != null &&
-			((text = ((JButton)c).getText()) == null || text.isEmpty());
+		if( !(c instanceof JButton) )
+			return false;
+
+		Icon icon = ((JButton)c).getIcon();
+		String text = ((JButton)c).getText();
+		return (icon != null && (text == null || text.isEmpty())) ||
+			(icon == null && text != null && ("...".equals( text ) || text.length() == 1));
 	}
 
 	static boolean isHelpButton( Component c ) {
@@ -295,8 +298,11 @@ public class FlatButtonUI
 
 		Dimension prefSize = super.getPreferredSize( c );
 
-		// apply minimum width, if not in toolbar and not a icon-only button
-		if( !isToolBarButton( c ) && !isIconOnlyButton( c ) )
+		// make button square if it is a icon-only button
+		// or apply minimum width, if not in toolbar and not a icon-only button
+		if( isIconOnlyButton( c ) )
+			prefSize.width = Math.max( prefSize.width, prefSize.height );
+		else if( !isToolBarButton( c ) )
 			prefSize.width = Math.max( prefSize.width, scale( minimumWidth + (focusWidth * 2) ) );
 
 		return prefSize;

flatlaf-testing/src/main/java/com/formdev/flatlaf/testing/FlatComponentsTest.java

@@ -58,6 +58,9 @@ public class FlatComponentsTest
 		JButton button3 = new JButton();
 		JButton button12 = new JButton();
 		JButton button13 = new JButton();
+		JButton button14 = new JButton();
+		JButton button15 = new JButton();
+		JButton button16 = new JButton();
 		JLabel toggleButtonLabel = new JLabel();
 		JToggleButton toggleButton1 = new JToggleButton();
 		JToggleButton toggleButton2 = new JToggleButton();
@@ -263,6 +266,18 @@ public class FlatComponentsTest
 		button13.setIcon(UIManager.getIcon("Tree.closedIcon"));
 		add(button13, "cell 5 1");
 
+		//---- button14 ----
+		button14.setText("...");
+		add(button14, "cell 5 1");
+
+		//---- button15 ----
+		button15.setText("\u2026");
+		add(button15, "cell 5 1");
+
+		//---- button16 ----
+		button16.setText("#");
+		add(button16, "cell 5 1");
+
 		//---- toggleButtonLabel ----
 		toggleButtonLabel.setText("JToggleButton:");
 		add(toggleButtonLabel, "cell 0 2");

flatlaf-testing/src/main/java/com/formdev/flatlaf/testing/FlatComponentsTest.jfd

@@ -85,6 +85,24 @@ new FormModel {
 			}, new FormLayoutConstraints( class net.miginfocom.layout.CC ) {
 				"value": "cell 5 1"
 			} )
+			add( new FormComponent( "javax.swing.JButton" ) {
+				name: "button14"
+				"text": "..."
+			}, new FormLayoutConstraints( class net.miginfocom.layout.CC ) {
+				"value": "cell 5 1"
+			} )
+			add( new FormComponent( "javax.swing.JButton" ) {
+				name: "button15"
+				"text": "…"
+			}, new FormLayoutConstraints( class net.miginfocom.layout.CC ) {
+				"value": "cell 5 1"
+			} )
+			add( new FormComponent( "javax.swing.JButton" ) {
+				name: "button16"
+				"text": "#"
+			}, new FormLayoutConstraints( class net.miginfocom.layout.CC ) {
+				"value": "cell 5 1"
+			} )
 			add( new FormComponent( "javax.swing.JLabel" ) {
 				name: "toggleButtonLabel"
 				"text": "JToggleButton:"