support different component border colors to indicate errors, warnings or custom state (set client property JComponent.outline to error, warning or any java.awt.Color)

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

@@ -114,6 +114,14 @@ class BasicComponentsPanel
 		JScrollPane scrollPane12 = new JScrollPane();
 		JTextPane textPane4 = new JTextPane();
 		JTextPane textPane5 = new JTextPane();
+		JLabel label3 = new JLabel();
+		JTextField textField5 = new JTextField();
+		JComboBox comboBox7 = new JComboBox();
+		JSpinner spinner3 = new JSpinner();
+		JLabel label4 = new JLabel();
+		JTextField textField7 = new JTextField();
+		JComboBox comboBox8 = new JComboBox();
+		JSpinner spinner4 = new JSpinner();
 		JPopupMenu popupMenu1 = new JPopupMenu();
 		JMenuItem cutMenuItem = new JMenuItem();
 		JMenuItem copyMenuItem = new JMenuItem();
@@ -141,6 +149,8 @@ class BasicComponentsPanel
 			"[]" +
 			"[]" +
 			"[]" +
+			"[]para" +
+			"[]" +
 			"[]"));
 
 		//---- labelLabel ----
@@ -596,6 +606,38 @@ class BasicComponentsPanel
 		textPane5.setText("no scroll pane");
 		add(textPane5, "cell 5 11,growx");
 
+		//---- label3 ----
+		label3.setText("Error:");
+		add(label3, "cell 0 12");
+
+		//---- textField5 ----
+		textField5.putClientProperty("JComponent.outline", "error");
+		add(textField5, "cell 1 12,growx");
+
+		//---- comboBox7 ----
+		comboBox7.putClientProperty("JComponent.outline", "error");
+		add(comboBox7, "cell 2 12,growx");
+
+		//---- spinner3 ----
+		spinner3.putClientProperty("JComponent.outline", "error");
+		add(spinner3, "cell 3 12,growx");
+
+		//---- label4 ----
+		label4.setText("Warning:");
+		add(label4, "cell 0 13");
+
+		//---- textField7 ----
+		textField7.putClientProperty("JComponent.outline", "warning");
+		add(textField7, "cell 1 13,growx");
+
+		//---- comboBox8 ----
+		comboBox8.putClientProperty("JComponent.outline", "warning");
+		add(comboBox8, "cell 2 13,growx");
+
+		//---- spinner4 ----
+		spinner4.putClientProperty("JComponent.outline", "warning");
+		add(spinner4, "cell 3 13,growx");
+
 		//======== popupMenu1 ========
 		{
 

flatlaf-demo/src/main/java/com/formdev/flatlaf/demo/BasicComponentsPanel.jfd

@@ -9,7 +9,7 @@ new FormModel {
 		add( new FormContainer( "javax.swing.JPanel", new FormLayoutManager( class net.miginfocom.swing.MigLayout ) {
 			"$layoutConstraints": "hidemode 3"
 			"$columnConstraints": "[][][][][][]"
-			"$rowConstraints": "[][][][][][][][][][][][]"
+			"$rowConstraints": "[][][][][][][][][][][][]para[][]"
 		} ) {
 			name: "this"
 			add( new FormComponent( "javax.swing.JLabel" ) {
@@ -591,9 +591,57 @@ new FormModel {
 			}, new FormLayoutConstraints( class net.miginfocom.layout.CC ) {
 				"value": "cell 5 11,growx"
 			} )
+			add( new FormComponent( "javax.swing.JLabel" ) {
+				name: "label3"
+				"text": "Error:"
+			}, new FormLayoutConstraints( class net.miginfocom.layout.CC ) {
+				"value": "cell 0 12"
+			} )
+			add( new FormComponent( "javax.swing.JTextField" ) {
+				name: "textField5"
+				"$client.JComponent.outline": "error"
+			}, new FormLayoutConstraints( class net.miginfocom.layout.CC ) {
+				"value": "cell 1 12,growx"
+			} )
+			add( new FormComponent( "javax.swing.JComboBox" ) {
+				name: "comboBox7"
+				"$client.JComponent.outline": "error"
+			}, new FormLayoutConstraints( class net.miginfocom.layout.CC ) {
+				"value": "cell 2 12,growx"
+			} )
+			add( new FormComponent( "javax.swing.JSpinner" ) {
+				name: "spinner3"
+				"$client.JComponent.outline": "error"
+			}, new FormLayoutConstraints( class net.miginfocom.layout.CC ) {
+				"value": "cell 3 12,growx"
+			} )
+			add( new FormComponent( "javax.swing.JLabel" ) {
+				name: "label4"
+				"text": "Warning:"
+			}, new FormLayoutConstraints( class net.miginfocom.layout.CC ) {
+				"value": "cell 0 13"
+			} )
+			add( new FormComponent( "javax.swing.JTextField" ) {
+				name: "textField7"
+				"$client.JComponent.outline": "warning"
+			}, new FormLayoutConstraints( class net.miginfocom.layout.CC ) {
+				"value": "cell 1 13,growx"
+			} )
+			add( new FormComponent( "javax.swing.JComboBox" ) {
+				name: "comboBox8"
+				"$client.JComponent.outline": "warning"
+			}, new FormLayoutConstraints( class net.miginfocom.layout.CC ) {
+				"value": "cell 2 13,growx"
+			} )
+			add( new FormComponent( "javax.swing.JSpinner" ) {
+				name: "spinner4"
+				"$client.JComponent.outline": "warning"
+			}, new FormLayoutConstraints( class net.miginfocom.layout.CC ) {
+				"value": "cell 3 13,growx"
+			} )
 		}, new FormLayoutConstraints( null ) {
 			"location": new java.awt.Point( 0, 0 )
-			"size": new java.awt.Dimension( 790, 440 )
+			"size": new java.awt.Dimension( 920, 440 )
 		} )
 		add( new FormContainer( "javax.swing.JPopupMenu", new FormLayoutManager( class javax.swing.JPopupMenu ) ) {
 			name: "popupMenu1"