List, Table and Tree: added colors for drag-and-drop

- added "enable drag and drop" checkbox to Demo on "Data Components" tab
- support copying UI default values lazy

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

@@ -32,6 +32,7 @@ import java.util.ServiceLoader;
 import java.util.function.Function;
 import java.util.logging.Level;
 import javax.swing.UIDefaults;
+import javax.swing.UIManager;
 import javax.swing.UIDefaults.ActiveValue;
 import javax.swing.UIDefaults.LazyValue;
 import javax.swing.plaf.ColorUIResource;
@@ -227,6 +228,15 @@ class UIDefaultsLoader
 			case "true":	return true;
 		}
 
+		// check for function "lazy"
+		//     Syntax: lazy(uiKey)
+		if( value.startsWith( "lazy(" ) && value.endsWith( ")" ) ) {
+			String uiKey = value.substring( 5, value.length() - 1 ).trim();
+			return (LazyValue) t -> {
+				return lazyUIManagerGet( uiKey );
+			};
+		}
+
 		ValueType valueType = ValueType.UNKNOWN;
 
 		// check whether value type is specified in the value
@@ -281,7 +291,7 @@ class UIDefaultsLoader
 			case UNKNOWN:
 			default:
 				// colors
-				ColorUIResource color = parseColorOrFunction( value, resolver, false );
+				Object color = parseColorOrFunction( value, resolver, false );
 				if( color != null )
 					return color;
 
@@ -301,7 +311,7 @@ class UIDefaultsLoader
 			List<String> parts = split( value, ',' );
 			Insets insets = parseInsets( value );
 			ColorUIResource lineColor = (parts.size() == 5)
-				? parseColorOrFunction( resolver.apply( parts.get( 4 ) ), resolver, true )
+				? (ColorUIResource) parseColorOrFunction( resolver.apply( parts.get( 4 ) ), resolver, true )
 				: null;
 
 			return (LazyValue) t -> {
@@ -377,7 +387,7 @@ class UIDefaultsLoader
 		}
 	}
 
-	private static ColorUIResource parseColorOrFunction( String value, Function<String, String> resolver, boolean reportError ) {
+	private static Object parseColorOrFunction( String value, Function<String, String> resolver, boolean reportError ) {
 		if( value.endsWith( ")" ) )
 			return parseColorFunctions( value, resolver, reportError );
 
@@ -447,7 +457,7 @@ class UIDefaultsLoader
 			: (((n >> 8) & 0xffffff) | ((n & 0xff) << 24)); // move alpha from lowest to highest byte
 	}
 
-	private static ColorUIResource parseColorFunctions( String value, Function<String, String> resolver, boolean reportError ) {
+	private static Object parseColorFunctions( String value, Function<String, String> resolver, boolean reportError ) {
 		int paramsStart = value.indexOf( '(' );
 		if( paramsStart < 0 ) {
 			if( reportError )
@@ -511,9 +521,9 @@ class UIDefaultsLoader
 	 * Syntax: lighten([color,]amount[,options]) or darken([color,]amount[,options])
 	 *   - color: a color (e.g. #f00) or a color function
 	 *   - amount: percentage 0-100%
-	 *   - options: [relative] [autoInverse]
+	 *   - options: [relative] [autoInverse] [lazy]
 	 */
-	private static ColorUIResource parseColorLightenOrDarken( boolean lighten, List<String> params,
+	private static Object parseColorLightenOrDarken( boolean lighten, List<String> params,
 		Function<String, String> resolver, boolean reportError )
 	{
 		boolean isDerived = params.get( 0 ).endsWith( "%" );
@@ -522,11 +532,13 @@ class UIDefaultsLoader
 		int amount = parsePercentage( params.get( nextParam++ ) );
 		boolean relative = false;
 		boolean autoInverse = false;
+		boolean lazy = false;
 
 		if( params.size() > nextParam ) {
 			String options = params.get( nextParam++ );
 			relative = options.contains( "relative" );
 			autoInverse = options.contains( "autoInverse" );
+			lazy = options.contains( "lazy" );
 		}
 
 		ColorFunctions.ColorFunction function = lighten
@@ -536,7 +548,16 @@ class UIDefaultsLoader
 		if( isDerived )
 			return new DerivedColor( function );
 
-		ColorUIResource color = parseColorOrFunction( resolver.apply( colorStr ), resolver, reportError );
+		if( lazy ) {
+			return (LazyValue) t -> {
+				Object color = lazyUIManagerGet( colorStr );
+				return (color instanceof Color)
+					? new ColorUIResource( ColorFunctions.applyFunctions( (Color) color, function ) )
+					: null;
+			};
+		}
+
+		ColorUIResource color = (ColorUIResource) parseColorOrFunction( resolver.apply( colorStr ), resolver, reportError );
 		return new ColorUIResource( ColorFunctions.applyFunctions( color, function ) );
 	}
 
@@ -618,4 +639,21 @@ class UIDefaultsLoader
 
 		return strs;
 	}
+
+	/**
+	 * For use in LazyValue to get value for given key from UIManager and report error
+	 * if not found. If key is prefixed by '?', then no error is reported.
+	 */
+	private static Object lazyUIManagerGet( String uiKey ) {
+		boolean optional = false;
+		if( uiKey.startsWith( OPTIONAL_PREFIX ) ) {
+			uiKey = uiKey.substring( OPTIONAL_PREFIX.length() );
+			optional = true;
+		}
+
+		Object value = UIManager.get( uiKey );
+		if( value == null && !optional )
+			FlatLaf.LOG.log( Level.SEVERE, "FlatLaf: '" + uiKey + "' not found in UI defaults." );
+		return value;
+	}
 }

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

@@ -35,6 +35,12 @@
 @buttonHoverBackground=lighten(3%,autoInverse)
 @buttonPressedBackground=lighten(6%,autoInverse)
 
+# Drop (use lazy colors for IntelliJ platform themes, which usually do not specify these colors)
+@dropCellBackground=darken(List.selectionBackground,10%,lazy)
+@dropCellForeground=lazy(List.selectionForeground)
+@dropLineColor=lighten(List.selectionBackground,10%,lazy)
+@dropLineShortColor=lighten(List.selectionBackground,30%,lazy)
+
 
 #---- globals ----
 

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

@@ -203,6 +203,9 @@ List.focusCellHighlightBorder=com.formdev.flatlaf.ui.FlatListCellBorder$Focused
 List.focusSelectedCellHighlightBorder=com.formdev.flatlaf.ui.FlatListCellBorder$Selected
 List.selectionInactiveBackground=@selectionInactiveBackground
 List.selectionInactiveForeground=@selectionInactiveForeground
+List.dropCellBackground=@dropCellBackground
+List.dropCellForeground=@dropCellForeground
+List.dropLineColor=@dropLineColor
 
 
 #---- Menu ----
@@ -376,6 +379,10 @@ Table.cellNoFocusBorder=2,3,2,3
 Table.focusSelectedCellHighlightBorder=2,3,2,3,@cellFocusColor
 Table.selectionInactiveBackground=@selectionInactiveBackground
 Table.selectionInactiveForeground=@selectionInactiveForeground
+Table.dropCellBackground=@dropCellBackground
+Table.dropCellForeground=@dropCellForeground
+Table.dropLineColor=@dropLineColor
+Table.dropLineShortColor=@dropLineShortColor
 
 
 #---- TableHeader ----
@@ -455,6 +462,9 @@ Tree.selectionInactiveBackground=@selectionInactiveBackground
 Tree.selectionInactiveForeground=@selectionInactiveForeground
 Tree.textBackground=null
 Tree.selectionBorderColor=@cellFocusColor
+Tree.dropCellBackground=@dropCellBackground
+Tree.dropCellForeground=@dropCellForeground
+Tree.dropLineColor=@dropLineColor
 Tree.rendererMargins=1,2,1,2
 Tree.wideSelection=true
 Tree.paintLines=false

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

@@ -35,6 +35,12 @@
 @buttonHoverBackground=darken(3%,autoInverse)
 @buttonPressedBackground=darken(10%,autoInverse)
 
+# Drop (use lazy colors for IntelliJ platform themes, which usually do not specify these colors)
+@dropCellBackground=lighten(List.selectionBackground,10%,lazy)
+@dropCellForeground=lazy(List.selectionForeground)
+@dropLineColor=lighten(List.selectionBackground,20%,lazy)
+@dropLineShortColor=darken(List.selectionBackground,20%,lazy)
+
 
 #---- globals ----
 

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

@@ -16,6 +16,9 @@
 
 package com.formdev.flatlaf.demo;
 
+import java.awt.datatransfer.DataFlavor;
+import java.awt.datatransfer.StringSelection;
+import java.awt.datatransfer.Transferable;
 import javax.swing.*;
 import javax.swing.table.*;
 import net.miginfocom.swing.*;
@@ -30,22 +33,53 @@ class DataComponentsPanel
 		initComponents();
 	}
 
+	private void dndChanged() {
+		boolean dnd = dndCheckBox.isSelected();
+		list1.setDragEnabled( dnd );
+		list2.setDragEnabled( dnd );
+		tree1.setDragEnabled( dnd );
+		tree2.setDragEnabled( dnd );
+		table1.setDragEnabled( dnd );
+
+		DropMode dropMode = dnd ? DropMode.ON_OR_INSERT : DropMode.USE_SELECTION;
+		list1.setDropMode( dropMode );
+		tree1.setDropMode( dropMode );
+		table1.setDropMode( dropMode );
+
+		String key = "FlatLaf.oldTransferHandler";
+		if( dnd ) {
+			list1.putClientProperty( key, list1.getTransferHandler() );
+			list1.setTransferHandler( new DummyTransferHandler() );
+
+			tree1.putClientProperty( key, tree1.getTransferHandler() );
+			tree1.setTransferHandler( new DummyTransferHandler() );
+
+			table1.putClientProperty( key, table1.getTransferHandler() );
+			table1.setTransferHandler( new DummyTransferHandler() );
+		} else {
+			list1.setTransferHandler( (TransferHandler) list1.getClientProperty( key ) );
+			tree1.setTransferHandler( (TransferHandler) tree1.getClientProperty( key ) );
+			table1.setTransferHandler( (TransferHandler) table1.getClientProperty( key ) );
+		}
+	}
+
 	@SuppressWarnings( { "unchecked", "rawtypes" } )
 	private void initComponents() {
 		// JFormDesigner - Component initialization - DO NOT MODIFY  //GEN-BEGIN:initComponents
 		JLabel listLabel = new JLabel();
 		JScrollPane scrollPane1 = new JScrollPane();
-		JList<String> list1 = new JList<>();
+		list1 = new JList<>();
 		JScrollPane scrollPane2 = new JScrollPane();
-		JList<String> list2 = new JList<>();
+		list2 = new JList<>();
 		JLabel treeLabel = new JLabel();
 		JScrollPane scrollPane3 = new JScrollPane();
-		JTree tree1 = new JTree();
+		tree1 = new JTree();
 		JScrollPane scrollPane4 = new JScrollPane();
-		JTree tree2 = new JTree();
+		tree2 = new JTree();
 		JLabel tableLabel = new JLabel();
 		JScrollPane scrollPane5 = new JScrollPane();
-		JTable table1 = new JTable();
+		table1 = new JTable();
+		dndCheckBox = new JCheckBox();
 
 		//======== this ========
 		setLayout(new MigLayout(
@@ -57,7 +91,8 @@ class DataComponentsPanel
 			// rows
 			"[]" +
 			"[::200]" +
-			"[::150]"));
+			"[::150]" +
+			"[]"));
 
 		//---- listLabel ----
 		listLabel.setText("JList:");
@@ -65,15 +100,25 @@ class DataComponentsPanel
 
 		//======== scrollPane1 ========
 		{
-			scrollPane1.setVerticalScrollBarPolicy(ScrollPaneConstants.VERTICAL_SCROLLBAR_NEVER);
-			scrollPane1.setHorizontalScrollBarPolicy(ScrollPaneConstants.HORIZONTAL_SCROLLBAR_NEVER);
 
 			//---- list1 ----
 			list1.setModel(new AbstractListModel<String>() {
 				String[] values = {
-					"abc",
+					"item 1",
-					"de",
+					"item 2",
-					"f"
+					"item 3",
+					"item 4",
+					"item 5",
+					"item 6",
+					"item 7",
+					"item 8",
+					"item 9",
+					"item 10",
+					"item 11",
+					"item 12",
+					"item 13",
+					"item 14",
+					"item 15"
 				};
 				@Override
 				public int getSize() { return values.length; }
@@ -86,15 +131,25 @@ class DataComponentsPanel
 
 		//======== scrollPane2 ========
 		{
-			scrollPane2.setVerticalScrollBarPolicy(ScrollPaneConstants.VERTICAL_SCROLLBAR_NEVER);
-			scrollPane2.setHorizontalScrollBarPolicy(ScrollPaneConstants.HORIZONTAL_SCROLLBAR_NEVER);
 
 			//---- list2 ----
 			list2.setModel(new AbstractListModel<String>() {
 				String[] values = {
-					"abc",
+					"item 1",
-					"de",
+					"item 2",
-					"f"
+					"item 3",
+					"item 4",
+					"item 5",
+					"item 6",
+					"item 7",
+					"item 8",
+					"item 9",
+					"item 10",
+					"item 11",
+					"item 12",
+					"item 13",
+					"item 14",
+					"item 15"
 				};
 				@Override
 				public int getSize() { return values.length; }
@@ -115,6 +170,7 @@ class DataComponentsPanel
 
 			//---- tree1 ----
 			tree1.setShowsRootHandles(true);
+			tree1.setEditable(true);
 			scrollPane3.setViewportView(tree1);
 		}
 		add(scrollPane3, "cell 1 1,growx");
@@ -138,8 +194,18 @@ class DataComponentsPanel
 			//---- table1 ----
 			table1.setModel(new DefaultTableModel(
 				new Object[][] {
-					{"Item 1a", "Item 2a", "January", "July", 123, null},
+					{"item 1", "item 1b", "January", "July", 123, null},
-					{"Item 1b", "Item 2b", "February", "August", 456, true},
+					{"item 2", "item 2b", "February", "August", 456, true},
+					{"item 3", null, "March", null, null, null},
+					{"item 4", null, "April", null, null, null},
+					{"item 5", null, "May", null, null, null},
+					{"item 6", null, "June", null, null, null},
+					{"item 7", null, "July", null, null, null},
+					{"item 8", null, "August", null, null, null},
+					{"item 9", null, "September", null, null, null},
+					{"item 10", null, "October", null, null, null},
+					{"item 11", null, "November", null, null, null},
+					{"item 12", null, "December", null, null, null},
 				},
 				new String[] {
 					"Not editable", "Text", "Combo", "Combo Editable", "Integer", "Boolean"
@@ -197,11 +263,60 @@ class DataComponentsPanel
 			scrollPane5.setViewportView(table1);
 		}
 		add(scrollPane5, "cell 1 2 2 1,growx,width 300");
+
+		//---- dndCheckBox ----
+		dndCheckBox.setText("enable drag and drop");
+		dndCheckBox.setMnemonic('D');
+		dndCheckBox.addActionListener(e -> dndChanged());
+		add(dndCheckBox, "cell 0 3 3 1");
 		// JFormDesigner - End of component initialization  //GEN-END:initComponents
 
 		((JComboBox)((DefaultCellEditor)table1.getColumnModel().getColumn( 3 ).getCellEditor()).getComponent()).setEditable( true );
 	}
 
 	// JFormDesigner - Variables declaration - DO NOT MODIFY  //GEN-BEGIN:variables
+	private JList<String> list1;
+	private JList<String> list2;
+	private JTree tree1;
+	private JTree tree2;
+	private JTable table1;
+	private JCheckBox dndCheckBox;
 	// JFormDesigner - End of variables declaration  //GEN-END:variables
+
+	//---- class DummyTransferHandler -----------------------------------------
+
+	private static class DummyTransferHandler
+		extends TransferHandler
+	{
+		@Override
+		protected Transferable createTransferable( JComponent c ) {
+			if( c instanceof JList && ((JList<?>)c).isSelectionEmpty() )
+				return null;
+			if( c instanceof JTree && ((JTree)c).isSelectionEmpty() )
+				return null;
+			if( c instanceof JTable && ((JTable)c).getSelectionModel().isSelectionEmpty() )
+				return null;
+
+			return new StringSelection( "dummy" );
+		}
+
+		@Override
+		public int getSourceActions( JComponent c ) {
+			return COPY;
+		}
+
+		@Override
+		public boolean canImport( TransferSupport support ) {
+			return support.isDataFlavorSupported( DataFlavor.stringFlavor );
+		}
+
+		@Override
+		public boolean importData( TransferSupport support ) {
+			String message = String.valueOf( support.getDropLocation() );
+			SwingUtilities.invokeLater( () -> {
+				JOptionPane.showMessageDialog( null, message, "Drop", JOptionPane.PLAIN_MESSAGE );
+			} );
+			return false;
+		}
+	}
 }

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

@@ -9,7 +9,7 @@ new FormModel {
 		add( new FormContainer( "javax.swing.JPanel", new FormLayoutManager( class net.miginfocom.swing.MigLayout ) {
 			"$layoutConstraints": "hidemode 3"
 			"$columnConstraints": "[][200][200]"
-			"$rowConstraints": "[][::200][::150]"
+			"$rowConstraints": "[][::200][::150][]"
 		} ) {
 			name: "this"
 			add( new FormComponent( "javax.swing.JLabel" ) {
@@ -20,17 +20,28 @@ new FormModel {
 			} )
 			add( new FormContainer( "javax.swing.JScrollPane", new FormLayoutManager( class javax.swing.JScrollPane ) ) {
 				name: "scrollPane1"
-				"verticalScrollBarPolicy": 21
-				"horizontalScrollBarPolicy": 31
 				add( new FormComponent( "javax.swing.JList" ) {
 					name: "list1"
-					"model": &DefaultListModel0 new javax.swing.DefaultListModel {
+					"model": new javax.swing.DefaultListModel {
-						addElement( "abc" )
+						addElement( "item 1" )
-						addElement( "de" )
+						addElement( "item 2" )
-						addElement( "f" )
+						addElement( "item 3" )
+						addElement( "item 4" )
+						addElement( "item 5" )
+						addElement( "item 6" )
+						addElement( "item 7" )
+						addElement( "item 8" )
+						addElement( "item 9" )
+						addElement( "item 10" )
+						addElement( "item 11" )
+						addElement( "item 12" )
+						addElement( "item 13" )
+						addElement( "item 14" )
+						addElement( "item 15" )
 					}
 					auxiliary() {
 						"JavaCodeGenerator.typeParameters": "String"
+						"JavaCodeGenerator.variableLocal": false
 					}
 				} )
 			}, new FormLayoutConstraints( class net.miginfocom.layout.CC ) {
@@ -38,14 +49,29 @@ new FormModel {
 			} )
 			add( new FormContainer( "javax.swing.JScrollPane", new FormLayoutManager( class javax.swing.JScrollPane ) ) {
 				name: "scrollPane2"
-				"verticalScrollBarPolicy": 21
-				"horizontalScrollBarPolicy": 31
 				add( new FormComponent( "javax.swing.JList" ) {
 					name: "list2"
-					"model": #DefaultListModel0
+					"model": new javax.swing.DefaultListModel {
+						addElement( "item 1" )
+						addElement( "item 2" )
+						addElement( "item 3" )
+						addElement( "item 4" )
+						addElement( "item 5" )
+						addElement( "item 6" )
+						addElement( "item 7" )
+						addElement( "item 8" )
+						addElement( "item 9" )
+						addElement( "item 10" )
+						addElement( "item 11" )
+						addElement( "item 12" )
+						addElement( "item 13" )
+						addElement( "item 14" )
+						addElement( "item 15" )
+					}
 					"enabled": false
 					auxiliary() {
 						"JavaCodeGenerator.typeParameters": "String"
+						"JavaCodeGenerator.variableLocal": false
 					}
 				} )
 			}, new FormLayoutConstraints( class net.miginfocom.layout.CC ) {
@@ -62,6 +88,10 @@ new FormModel {
 				add( new FormComponent( "javax.swing.JTree" ) {
 					name: "tree1"
 					"showsRootHandles": true
+					"editable": true
+					auxiliary() {
+						"JavaCodeGenerator.variableLocal": false
+					}
 				} )
 			}, new FormLayoutConstraints( class net.miginfocom.layout.CC ) {
 				"value": "cell 1 1,growx"
@@ -71,6 +101,9 @@ new FormModel {
 				add( new FormComponent( "javax.swing.JTree" ) {
 					name: "tree2"
 					"enabled": false
+					auxiliary() {
+						"JavaCodeGenerator.variableLocal": false
+					}
 				} )
 			}, new FormLayoutConstraints( class net.miginfocom.layout.CC ) {
 				"value": "cell 2 1,growx"
@@ -87,21 +120,101 @@ new FormModel {
 					name: "table1"
 					"model": new com.jformdesigner.model.SwingTableModel( new java.util.Vector {
 						add( new java.util.Vector {
-							add( "Item 1a" )
+							add( "item 1" )
-							add( "Item 2a" )
+							add( "item 1b" )
 							add( "January" )
 							add( "July" )
 							add( 123 )
 							add( null )
 						} )
 						add( new java.util.Vector {
-							add( "Item 1b" )
+							add( "item 2" )
-							add( "Item 2b" )
+							add( "item 2b" )
 							add( "February" )
 							add( "August" )
 							add( 456 )
 							add( true )
 						} )
+						add( new java.util.Vector {
+							add( "item 3" )
+							add( null )
+							add( "March" )
+							add( null )
+							add( null )
+							add( null )
+						} )
+						add( new java.util.Vector {
+							add( "item 4" )
+							add( null )
+							add( "April" )
+							add( null )
+							add( null )
+							add( null )
+						} )
+						add( new java.util.Vector {
+							add( "item 5" )
+							add( null )
+							add( "May" )
+							add( null )
+							add( null )
+							add( null )
+						} )
+						add( new java.util.Vector {
+							add( "item 6" )
+							add( null )
+							add( "June" )
+							add( null )
+							add( null )
+							add( null )
+						} )
+						add( new java.util.Vector {
+							add( "item 7" )
+							add( null )
+							add( "July" )
+							add( null )
+							add( null )
+							add( null )
+						} )
+						add( new java.util.Vector {
+							add( "item 8" )
+							add( null )
+							add( "August" )
+							add( null )
+							add( null )
+							add( null )
+						} )
+						add( new java.util.Vector {
+							add( "item 9" )
+							add( null )
+							add( "September" )
+							add( null )
+							add( null )
+							add( null )
+						} )
+						add( new java.util.Vector {
+							add( "item 10" )
+							add( null )
+							add( "October" )
+							add( null )
+							add( null )
+							add( null )
+						} )
+						add( new java.util.Vector {
+							add( "item 11" )
+							add( null )
+							add( "November" )
+							add( null )
+							add( null )
+							add( null )
+						} )
+						add( new java.util.Vector {
+							add( "item 12" )
+							add( null )
+							add( "December" )
+							add( null )
+							add( null )
+							add( null )
+						} )
 					}, new java.util.Vector {
 						add( "Not editable" )
 						add( "Text" )
@@ -132,10 +245,24 @@ new FormModel {
 						add( null )
 					} )
 					"autoCreateRowSorter": true
+					auxiliary() {
+						"JavaCodeGenerator.variableLocal": false
+					}
 				} )
 			}, new FormLayoutConstraints( class net.miginfocom.layout.CC ) {
 				"value": "cell 1 2 2 1,growx,width 300"
 			} )
+			add( new FormComponent( "javax.swing.JCheckBox" ) {
+				name: "dndCheckBox"
+				"text": "enable drag and drop"
+				"mnemonic": 68
+				auxiliary() {
+					"JavaCodeGenerator.variableLocal": false
+				}
+				addEvent( new FormEvent( "java.awt.event.ActionListener", "actionPerformed", "dndChanged", false ) )
+			}, new FormLayoutConstraints( class net.miginfocom.layout.CC ) {
+				"value": "cell 0 3 3 1"
+			} )
 		}, new FormLayoutConstraints( null ) {
 			"location": new java.awt.Point( 0, 0 )
 			"size": new java.awt.Dimension( 790, 715 )

flatlaf-testing/src/main/java/com/formdev/flatlaf/testing/FlatComponents2Test.java

@@ -16,6 +16,9 @@
 
 package com.formdev.flatlaf.testing;
 
+import java.awt.datatransfer.DataFlavor;
+import java.awt.datatransfer.StringSelection;
+import java.awt.datatransfer.Transferable;
 import javax.swing.*;
 import javax.swing.table.*;
 import net.miginfocom.swing.*;
@@ -37,28 +40,56 @@ public class FlatComponents2Test
 		initComponents();
 	}
 
+	private void dndChanged() {
+		boolean dnd = dndCheckBox.isSelected();
+		list1.setDragEnabled( dnd );
+		list2.setDragEnabled( dnd );
+		tree1.setDragEnabled( dnd );
+		tree2.setDragEnabled( dnd );
+		table1.setDragEnabled( dnd );
+
+		DropMode dropMode = dnd ? DropMode.ON_OR_INSERT : DropMode.USE_SELECTION;
+		list1.setDropMode( dropMode );
+		tree1.setDropMode( dropMode );
+		table1.setDropMode( dropMode );
+
+		String key = "FlatLaf.oldTransferHandler";
+		if( dnd ) {
+			list1.putClientProperty( key, list1.getTransferHandler() );
+			list1.setTransferHandler( new DummyTransferHandler() );
+
+			tree1.putClientProperty( key, tree1.getTransferHandler() );
+			tree1.setTransferHandler( new DummyTransferHandler() );
+
+			table1.putClientProperty( key, table1.getTransferHandler() );
+			table1.setTransferHandler( new DummyTransferHandler() );
+		} else {
+			list1.setTransferHandler( (TransferHandler) list1.getClientProperty( key ) );
+			tree1.setTransferHandler( (TransferHandler) tree1.getClientProperty( key ) );
+			table1.setTransferHandler( (TransferHandler) table1.getClientProperty( key ) );
+		}
+	}
+
 	@SuppressWarnings( { "unchecked", "rawtypes" } )
 	private void initComponents() {
 		// JFormDesigner - Component initialization - DO NOT MODIFY  //GEN-BEGIN:initComponents
-		JLabel labelLabel = new JLabel();
-		JLabel label1 = new JLabel();
-		JLabel label2 = new JLabel();
 		JLabel textFieldLabel = new JLabel();
 		JTextField textField1 = new JTextField();
 		JTextField textField2 = new JTextField();
 		JLabel listLabel = new JLabel();
 		JScrollPane scrollPane1 = new JScrollPane();
-		JList<String> list1 = new JList<>();
+		list1 = new JList<>();
 		JScrollPane scrollPane2 = new JScrollPane();
-		JList<String> list2 = new JList<>();
+		list2 = new JList<>();
 		JLabel treeLabel = new JLabel();
 		JScrollPane scrollPane3 = new JScrollPane();
-		JTree tree1 = new JTree();
+		tree1 = new JTree();
 		JScrollPane scrollPane4 = new JScrollPane();
-		JTree tree2 = new JTree();
+		tree2 = new JTree();
 		JLabel tableLabel = new JLabel();
 		JScrollPane scrollPane5 = new JScrollPane();
-		JTable table1 = new JTable();
+		table1 = new JTable();
+		dndCheckBox = new JCheckBox();
 
 		//======== this ========
 		setLayout(new MigLayout(
@@ -70,53 +101,48 @@ public class FlatComponents2Test
 			// rows
 			"[]" +
 			"[]" +
-			"[]" +
 			"[::200]" +
-			"[::150]"));
+			"[::150]" +
-
+			"[]"));
-		//---- labelLabel ----
-		labelLabel.setText("JLabel:");
-		add(labelLabel, "cell 0 0");
-
-		//---- label1 ----
-		label1.setText("enabled");
-		label1.setDisplayedMnemonic('E');
-		add(label1, "cell 1 0");
-
-		//---- label2 ----
-		label2.setText("disabled");
-		label2.setDisplayedMnemonic('D');
-		label2.setEnabled(false);
-		add(label2, "cell 2 0");
 
 		//---- textFieldLabel ----
 		textFieldLabel.setText("JTextField:");
-		add(textFieldLabel, "cell 0 1");
+		add(textFieldLabel, "cell 0 0");
 
 		//---- textField1 ----
 		textField1.setText("editable");
-		add(textField1, "cell 1 1,growx");
+		add(textField1, "cell 1 0,growx");
 
 		//---- textField2 ----
 		textField2.setText("disabled");
 		textField2.setEnabled(false);
-		add(textField2, "cell 2 1,growx");
+		add(textField2, "cell 2 0,growx");
 
 		//---- listLabel ----
 		listLabel.setText("JList:");
-		add(listLabel, "cell 0 2");
+		add(listLabel, "cell 0 1");
 
 		//======== scrollPane1 ========
 		{
-			scrollPane1.setVerticalScrollBarPolicy(ScrollPaneConstants.VERTICAL_SCROLLBAR_NEVER);
-			scrollPane1.setHorizontalScrollBarPolicy(ScrollPaneConstants.HORIZONTAL_SCROLLBAR_NEVER);
 
 			//---- list1 ----
 			list1.setModel(new AbstractListModel<String>() {
 				String[] values = {
-					"abc",
+					"item 1",
-					"de",
+					"item 2",
-					"f"
+					"item 3",
+					"item 4",
+					"item 5",
+					"item 6",
+					"item 7",
+					"item 8",
+					"item 9",
+					"item 10",
+					"item 11",
+					"item 12",
+					"item 13",
+					"item 14",
+					"item 15"
 				};
 				@Override
 				public int getSize() { return values.length; }
@@ -125,19 +151,29 @@ public class FlatComponents2Test
 			});
 			scrollPane1.setViewportView(list1);
 		}
-		add(scrollPane1, "cell 1 2,growx");
+		add(scrollPane1, "cell 1 1,growx");
 
 		//======== scrollPane2 ========
 		{
-			scrollPane2.setVerticalScrollBarPolicy(ScrollPaneConstants.VERTICAL_SCROLLBAR_NEVER);
-			scrollPane2.setHorizontalScrollBarPolicy(ScrollPaneConstants.HORIZONTAL_SCROLLBAR_NEVER);
 
 			//---- list2 ----
 			list2.setModel(new AbstractListModel<String>() {
 				String[] values = {
-					"abc",
+					"item 1",
-					"de",
+					"item 2",
-					"f"
+					"item 3",
+					"item 4",
+					"item 5",
+					"item 6",
+					"item 7",
+					"item 8",
+					"item 9",
+					"item 10",
+					"item 11",
+					"item 12",
+					"item 13",
+					"item 14",
+					"item 15"
 				};
 				@Override
 				public int getSize() { return values.length; }
@@ -147,11 +183,11 @@ public class FlatComponents2Test
 			list2.setEnabled(false);
 			scrollPane2.setViewportView(list2);
 		}
-		add(scrollPane2, "cell 2 2,growx");
+		add(scrollPane2, "cell 2 1,growx");
 
 		//---- treeLabel ----
 		treeLabel.setText("JTree:");
-		add(treeLabel, "cell 0 3");
+		add(treeLabel, "cell 0 2");
 
 		//======== scrollPane3 ========
 		{
@@ -161,7 +197,7 @@ public class FlatComponents2Test
 			tree1.setEditable(true);
 			scrollPane3.setViewportView(tree1);
 		}
-		add(scrollPane3, "cell 1 3,growx");
+		add(scrollPane3, "cell 1 2,growx");
 
 		//======== scrollPane4 ========
 		{
@@ -170,11 +206,11 @@ public class FlatComponents2Test
 			tree2.setEnabled(false);
 			scrollPane4.setViewportView(tree2);
 		}
-		add(scrollPane4, "cell 2 3,growx");
+		add(scrollPane4, "cell 2 2,growx");
 
 		//---- tableLabel ----
 		tableLabel.setText("JTable:");
-		add(tableLabel, "cell 0 4");
+		add(tableLabel, "cell 0 3");
 
 		//======== scrollPane5 ========
 		{
@@ -182,8 +218,18 @@ public class FlatComponents2Test
 			//---- table1 ----
 			table1.setModel(new DefaultTableModel(
 				new Object[][] {
-					{"Item 1a", "Item 2a", "January", "July", 123, null},
+					{"item 1", "item 1b", "January", "July", 123, null},
-					{"Item 1b", "Item 2b", "February", "August", 456, true},
+					{"item 2", "item 2b", "February", "August", 456, true},
+					{"item 3", null, "March", null, null, null},
+					{"item 4", null, "April", null, null, null},
+					{"item 5", null, "May", null, null, null},
+					{"item 6", null, "June", null, null, null},
+					{"item 7", null, "July", null, null, null},
+					{"item 8", null, "August", null, null, null},
+					{"item 9", null, "September", null, null, null},
+					{"item 10", null, "October", null, null, null},
+					{"item 11", null, "November", null, null, null},
+					{"item 12", null, "December", null, null, null},
 				},
 				new String[] {
 					"Not editable", "Text", "Combo", "Combo Editable", "Integer", "Boolean"
@@ -240,12 +286,58 @@ public class FlatComponents2Test
 			table1.setAutoCreateRowSorter(true);
 			scrollPane5.setViewportView(table1);
 		}
-		add(scrollPane5, "cell 1 4 2 1,growx,width 300");
+		add(scrollPane5, "cell 1 3 2 1,growx,width 300");
+
+		//---- dndCheckBox ----
+		dndCheckBox.setText("enable drag and drop");
+		dndCheckBox.setMnemonic('D');
+		dndCheckBox.addActionListener(e -> dndChanged());
+		add(dndCheckBox, "cell 0 4 3 1");
 		// JFormDesigner - End of component initialization  //GEN-END:initComponents
 
 		((JComboBox)((DefaultCellEditor)table1.getColumnModel().getColumn( 3 ).getCellEditor()).getComponent()).setEditable( true );
 	}
 
 	// JFormDesigner - Variables declaration - DO NOT MODIFY  //GEN-BEGIN:variables
+	private JList<String> list1;
+	private JList<String> list2;
+	private JTree tree1;
+	private JTree tree2;
+	private JTable table1;
+	private JCheckBox dndCheckBox;
 	// JFormDesigner - End of variables declaration  //GEN-END:variables
+
+	//---- class DummyTransferHandler -----------------------------------------
+
+	private static class DummyTransferHandler
+		extends TransferHandler
+	{
+		@Override
+		protected Transferable createTransferable( JComponent c ) {
+			if( c instanceof JList && ((JList<?>)c).isSelectionEmpty() )
+				return null;
+			if( c instanceof JTree && ((JTree)c).isSelectionEmpty() )
+				return null;
+			if( c instanceof JTable && ((JTable)c).getSelectionModel().isSelectionEmpty() )
+				return null;
+
+			return new StringSelection( "dummy" );
+		}
+
+		@Override
+		public int getSourceActions( JComponent c ) {
+			return COPY;
+		}
+
+		@Override
+		public boolean canImport( TransferSupport support ) {
+			return support.isDataFlavorSupported( DataFlavor.stringFlavor );
+		}
+
+		@Override
+		public boolean importData( TransferSupport support ) {
+			System.out.println( support.getDropLocation() );
+			return false;
+		}
+	}
 }

flatlaf-testing/src/main/java/com/formdev/flatlaf/testing/FlatComponents2Test.jfd

@@ -9,93 +9,98 @@ new FormModel {
 		add( new FormContainer( "com.formdev.flatlaf.testing.FlatTestPanel", new FormLayoutManager( class net.miginfocom.swing.MigLayout ) {
 			"$layoutConstraints": "ltr,insets dialog,hidemode 3"
 			"$columnConstraints": "[][200][200]"
-			"$rowConstraints": "[][][][::200][::150]"
+			"$rowConstraints": "[][][::200][::150][]"
 		} ) {
 			name: "this"
-			add( new FormComponent( "javax.swing.JLabel" ) {
-				name: "labelLabel"
-				"text": "JLabel:"
-			}, new FormLayoutConstraints( class net.miginfocom.layout.CC ) {
-				"value": "cell 0 0"
-			} )
-			add( new FormComponent( "javax.swing.JLabel" ) {
-				name: "label1"
-				"text": "enabled"
-				"displayedMnemonic": 69
-			}, new FormLayoutConstraints( class net.miginfocom.layout.CC ) {
-				"value": "cell 1 0"
-			} )
-			add( new FormComponent( "javax.swing.JLabel" ) {
-				name: "label2"
-				"text": "disabled"
-				"displayedMnemonic": 68
-				"enabled": false
-			}, new FormLayoutConstraints( class net.miginfocom.layout.CC ) {
-				"value": "cell 2 0"
-			} )
 			add( new FormComponent( "javax.swing.JLabel" ) {
 				name: "textFieldLabel"
 				"text": "JTextField:"
 			}, new FormLayoutConstraints( class net.miginfocom.layout.CC ) {
-				"value": "cell 0 1"
+				"value": "cell 0 0"
 			} )
 			add( new FormComponent( "javax.swing.JTextField" ) {
 				name: "textField1"
 				"text": "editable"
 			}, new FormLayoutConstraints( class net.miginfocom.layout.CC ) {
-				"value": "cell 1 1,growx"
+				"value": "cell 1 0,growx"
 			} )
 			add( new FormComponent( "javax.swing.JTextField" ) {
 				name: "textField2"
 				"text": "disabled"
 				"enabled": false
 			}, new FormLayoutConstraints( class net.miginfocom.layout.CC ) {
-				"value": "cell 2 1,growx"
+				"value": "cell 2 0,growx"
 			} )
 			add( new FormComponent( "javax.swing.JLabel" ) {
 				name: "listLabel"
 				"text": "JList:"
 			}, new FormLayoutConstraints( class net.miginfocom.layout.CC ) {
-				"value": "cell 0 2"
+				"value": "cell 0 1"
 			} )
 			add( new FormContainer( "javax.swing.JScrollPane", new FormLayoutManager( class javax.swing.JScrollPane ) ) {
 				name: "scrollPane1"
-				"verticalScrollBarPolicy": 21
-				"horizontalScrollBarPolicy": 31
 				add( new FormComponent( "javax.swing.JList" ) {
 					name: "list1"
-					"model": &DefaultListModel0 new javax.swing.DefaultListModel {
+					"model": new javax.swing.DefaultListModel {
-						addElement( "abc" )
+						addElement( "item 1" )
-						addElement( "de" )
+						addElement( "item 2" )
-						addElement( "f" )
+						addElement( "item 3" )
+						addElement( "item 4" )
+						addElement( "item 5" )
+						addElement( "item 6" )
+						addElement( "item 7" )
+						addElement( "item 8" )
+						addElement( "item 9" )
+						addElement( "item 10" )
+						addElement( "item 11" )
+						addElement( "item 12" )
+						addElement( "item 13" )
+						addElement( "item 14" )
+						addElement( "item 15" )
 					}
 					auxiliary() {
 						"JavaCodeGenerator.typeParameters": "String"
+						"JavaCodeGenerator.variableLocal": false
 					}
 				} )
 			}, new FormLayoutConstraints( class net.miginfocom.layout.CC ) {
-				"value": "cell 1 2,growx"
+				"value": "cell 1 1,growx"
 			} )
 			add( new FormContainer( "javax.swing.JScrollPane", new FormLayoutManager( class javax.swing.JScrollPane ) ) {
 				name: "scrollPane2"
-				"verticalScrollBarPolicy": 21
-				"horizontalScrollBarPolicy": 31
 				add( new FormComponent( "javax.swing.JList" ) {
 					name: "list2"
-					"model": #DefaultListModel0
+					"model": new javax.swing.DefaultListModel {
+						addElement( "item 1" )
+						addElement( "item 2" )
+						addElement( "item 3" )
+						addElement( "item 4" )
+						addElement( "item 5" )
+						addElement( "item 6" )
+						addElement( "item 7" )
+						addElement( "item 8" )
+						addElement( "item 9" )
+						addElement( "item 10" )
+						addElement( "item 11" )
+						addElement( "item 12" )
+						addElement( "item 13" )
+						addElement( "item 14" )
+						addElement( "item 15" )
+					}
 					"enabled": false
 					auxiliary() {
 						"JavaCodeGenerator.typeParameters": "String"
+						"JavaCodeGenerator.variableLocal": false
 					}
 				} )
 			}, new FormLayoutConstraints( class net.miginfocom.layout.CC ) {
-				"value": "cell 2 2,growx"
+				"value": "cell 2 1,growx"
 			} )
 			add( new FormComponent( "javax.swing.JLabel" ) {
 				name: "treeLabel"
 				"text": "JTree:"
 			}, new FormLayoutConstraints( class net.miginfocom.layout.CC ) {
-				"value": "cell 0 3"
+				"value": "cell 0 2"
 			} )
 			add( new FormContainer( "javax.swing.JScrollPane", new FormLayoutManager( class javax.swing.JScrollPane ) ) {
 				name: "scrollPane3"
@@ -103,24 +108,30 @@ new FormModel {
 					name: "tree1"
 					"showsRootHandles": true
 					"editable": true
+					auxiliary() {
+						"JavaCodeGenerator.variableLocal": false
+					}
 				} )
 			}, new FormLayoutConstraints( class net.miginfocom.layout.CC ) {
-				"value": "cell 1 3,growx"
+				"value": "cell 1 2,growx"
 			} )
 			add( new FormContainer( "javax.swing.JScrollPane", new FormLayoutManager( class javax.swing.JScrollPane ) ) {
 				name: "scrollPane4"
 				add( new FormComponent( "javax.swing.JTree" ) {
 					name: "tree2"
 					"enabled": false
+					auxiliary() {
+						"JavaCodeGenerator.variableLocal": false
+					}
 				} )
 			}, new FormLayoutConstraints( class net.miginfocom.layout.CC ) {
-				"value": "cell 2 3,growx"
+				"value": "cell 2 2,growx"
 			} )
 			add( new FormComponent( "javax.swing.JLabel" ) {
 				name: "tableLabel"
 				"text": "JTable:"
 			}, new FormLayoutConstraints( class net.miginfocom.layout.CC ) {
-				"value": "cell 0 4"
+				"value": "cell 0 3"
 			} )
 			add( new FormContainer( "javax.swing.JScrollPane", new FormLayoutManager( class javax.swing.JScrollPane ) ) {
 				name: "scrollPane5"
@@ -128,21 +139,101 @@ new FormModel {
 					name: "table1"
 					"model": new com.jformdesigner.model.SwingTableModel( new java.util.Vector {
 						add( new java.util.Vector {
-							add( "Item 1a" )
+							add( "item 1" )
-							add( "Item 2a" )
+							add( "item 1b" )
 							add( "January" )
 							add( "July" )
 							add( 123 )
 							add( null )
 						} )
 						add( new java.util.Vector {
-							add( "Item 1b" )
+							add( "item 2" )
-							add( "Item 2b" )
+							add( "item 2b" )
 							add( "February" )
 							add( "August" )
 							add( 456 )
 							add( true )
 						} )
+						add( new java.util.Vector {
+							add( "item 3" )
+							add( null )
+							add( "March" )
+							add( null )
+							add( null )
+							add( null )
+						} )
+						add( new java.util.Vector {
+							add( "item 4" )
+							add( null )
+							add( "April" )
+							add( null )
+							add( null )
+							add( null )
+						} )
+						add( new java.util.Vector {
+							add( "item 5" )
+							add( null )
+							add( "May" )
+							add( null )
+							add( null )
+							add( null )
+						} )
+						add( new java.util.Vector {
+							add( "item 6" )
+							add( null )
+							add( "June" )
+							add( null )
+							add( null )
+							add( null )
+						} )
+						add( new java.util.Vector {
+							add( "item 7" )
+							add( null )
+							add( "July" )
+							add( null )
+							add( null )
+							add( null )
+						} )
+						add( new java.util.Vector {
+							add( "item 8" )
+							add( null )
+							add( "August" )
+							add( null )
+							add( null )
+							add( null )
+						} )
+						add( new java.util.Vector {
+							add( "item 9" )
+							add( null )
+							add( "September" )
+							add( null )
+							add( null )
+							add( null )
+						} )
+						add( new java.util.Vector {
+							add( "item 10" )
+							add( null )
+							add( "October" )
+							add( null )
+							add( null )
+							add( null )
+						} )
+						add( new java.util.Vector {
+							add( "item 11" )
+							add( null )
+							add( "November" )
+							add( null )
+							add( null )
+							add( null )
+						} )
+						add( new java.util.Vector {
+							add( "item 12" )
+							add( null )
+							add( "December" )
+							add( null )
+							add( null )
+							add( null )
+						} )
 					}, new java.util.Vector {
 						add( "Not editable" )
 						add( "Text" )
@@ -173,9 +264,23 @@ new FormModel {
 						add( null )
 					} )
 					"autoCreateRowSorter": true
+					auxiliary() {
+						"JavaCodeGenerator.variableLocal": false
+					}
 				} )
 			}, new FormLayoutConstraints( class net.miginfocom.layout.CC ) {
-				"value": "cell 1 4 2 1,growx,width 300"
+				"value": "cell 1 3 2 1,growx,width 300"
+			} )
+			add( new FormComponent( "javax.swing.JCheckBox" ) {
+				name: "dndCheckBox"
+				"text": "enable drag and drop"
+				"mnemonic": 68
+				auxiliary() {
+					"JavaCodeGenerator.variableLocal": false
+				}
+				addEvent( new FormEvent( "java.awt.event.ActionListener", "actionPerformed", "dndChanged", false ) )
+			}, new FormLayoutConstraints( class net.miginfocom.layout.CC ) {
+				"value": "cell 0 4 3 1"
 			} )
 		}, new FormLayoutConstraints( null ) {
 			"location": new java.awt.Point( 0, 0 )

flatlaf-testing/src/main/resources/com/formdev/flatlaf/testing/FlatTestLaf.properties

@@ -27,6 +27,11 @@
 @cellFocusColor=#ff0000
 @icon=#afafaf
 
+@dropCellBackground=#f00
+@dropCellForeground=#0f0
+@dropLineColor=#00f
+@dropLineShortColor=#ff0
+
 
 #---- globals ----