Experiment for #97

demo-single-app/src/basic/MainFrame.java

@@ -224,6 +224,13 @@ public void setVisible(boolean visible) {
 		view.add(changeText);
 		view.add(actionListenDock(themes));
 
+		JMenuItem openDockableTabGroup = new JMenuItem("DockableTabGroup");
+		openDockableTabGroup.addActionListener( e-> {
+			DockableTabGroup group = new DockableTabGroup(new JPopupMenu(), JTabbedPane.TOP);
+			Docking.dock(group, two, one, DockingRegion.EAST);
+		});
+		view.add(openDockableTabGroup);
+
 		JMenuItem storeCurrentLayout = new JMenuItem("Store Current Layout...");
 		storeCurrentLayout.addActionListener(e -> {
 			String layoutName = JOptionPane.showInputDialog("Name of Layout");

docking-api/src/ModernDocking/DockableTabGroup.java

@@ -0,0 +1,43 @@
+/*
+Copyright (c) 2023 Andrew Auclair
+
+Permission is hereby granted, free of charge, to any person obtaining a copy
+of this software and associated documentation files (the "Software"), to deal
+in the Software without restriction, including without limitation the rights
+to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+copies of the Software, and to permit persons to whom the Software is
+furnished to do so, subject to the following conditions:
+
+The above copyright notice and this permission notice shall be included in all
+copies or substantial portions of the Software.
+
+THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+FITNESS FOR A PARTICULAR PURPOSE AND NON-INFRINGEMENT. IN NO EVENT SHALL THE
+AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
+SOFTWARE.
+ */
+package ModernDocking;
+
+import javax.swing.*;
+
+public class DockableTabGroup {
+    private final JPopupMenu contextMenu;
+    private final int tabPlacement;
+
+    public DockableTabGroup(JPopupMenu contextMenu, int tabPlacement) {
+
+        this.contextMenu = contextMenu;
+        this.tabPlacement = tabPlacement;
+    }
+
+    public JPopupMenu getContextMenu() {
+        return contextMenu;
+    }
+
+    public int getTabPlacement() {
+        return tabPlacement;
+    }
+}

docking-api/src/ModernDocking/api/DockingAPI.java

@@ -2,6 +2,7 @@
 
 import ModernDocking.Dockable;
 import ModernDocking.DockableStyle;
+import ModernDocking.DockableTabGroup;
 import ModernDocking.DockingRegion;
 import ModernDocking.event.DockingListener;
 import ModernDocking.event.MaximizeListener;
@@ -451,6 +452,20 @@ public void dock(Dockable source, Dockable target, DockingRegion region, double
         appState.persist();
     }
 
+    public void dock(DockableTabGroup group, Dockable firstDockable, Dockable target, DockingRegion region) {
+        if (!isDocked(target)) {
+            throw new NotDockedException(target);
+        }
+
+        if (isDocked(firstDockable)) {
+            undock(firstDockable);
+        }
+
+        DockableWrapper wrapper = internals.getWrapper(target);
+
+        wrapper.getParent().dock(group, firstDockable, region, 0.5);
+    }
+
     /**
      * create a new FloatingFrame window for the given dockable, undock it from its current frame (if there is one) and dock it into the new frame
      *

docking-api/src/ModernDocking/internal/DockedSimplePanel.java

@@ -22,6 +22,7 @@ of this software and associated documentation files (the "Software"), to deal
 package ModernDocking.internal;
 
 import ModernDocking.Dockable;
+import ModernDocking.DockableTabGroup;
 import ModernDocking.DockingRegion;
 import ModernDocking.api.DockingAPI;
 import ModernDocking.floating.FloatListener;
@@ -150,6 +151,42 @@ else if (region == DockingRegion.CENTER) {
 		repaint();
 	}
 
+	@Override
+	public void dock(DockableTabGroup group, Dockable firstDockable, DockingRegion region, double dividerProportion) {
+		if (region == DockingRegion.CENTER) {
+			return;
+		}
+
+		DockableWrapper wrapper = DockingInternal.get(docking).getWrapper(firstDockable);
+
+		DockedSplitPanel split = new DockedSplitPanel(docking, this.dockable.getWindow());
+		parent.replaceChild(this, split);
+
+		DockingPanel newPanel = new DockedTabbedPanel(docking, group, wrapper);
+
+		if (region == DockingRegion.EAST || region == DockingRegion.SOUTH) {
+			split.setLeft(this);
+			split.setRight(newPanel);
+			dividerProportion = 1.0 - dividerProportion;
+		}
+		else {
+			split.setLeft(newPanel);
+			split.setRight(this);
+		}
+
+		if (region == DockingRegion.EAST || region == DockingRegion.WEST) {
+			split.setOrientation(JSplitPane.HORIZONTAL_SPLIT);
+		}
+		else {
+			split.setOrientation(JSplitPane.VERTICAL_SPLIT);
+		}
+
+		split.setDividerLocation(dividerProportion);
+
+		repaint();
+		revalidate();
+	}
+
 	@Override
 	public void undock(Dockable dockable) {
 		if (this.dockable.getDockable() == dockable) {

docking-api/src/ModernDocking/internal/DockedTabbedPanel.java

@@ -22,6 +22,7 @@ of this software and associated documentation files (the "Software"), to deal
 package ModernDocking.internal;
 
 import ModernDocking.Dockable;
+import ModernDocking.DockableTabGroup;
 import ModernDocking.DockingRegion;
 import ModernDocking.api.DockingAPI;
 import ModernDocking.floating.FloatListener;
@@ -67,24 +68,35 @@ public class DockedTabbedPanel extends DockingPanel implements ChangeListener {
 
 	private static Icon settingsIcon = new ImageIcon(Objects.requireNonNull(DockedTabbedPanel.class.getResource("/icons/settings.png")));
 
+	private int tabPlacement;
+
 	/**
 	 * Create a new instance of DockedTabbedPanel
 	 *
 	 * @param dockable The first dockable in the tabbed pane
 	 */
 	public DockedTabbedPanel(DockingAPI docking, DockableWrapper dockable) {
+		this(docking, dockable, Settings.alwaysDisplayTabsMode());
+	}
+
+	public DockedTabbedPanel(DockingAPI docking, DockableWrapper dockable, boolean topTabs) {
 		this.docking = docking;
 		setLayout(new BorderLayout());
 
 		// set the initial border. Docking handles the border after this using a global AWT listener
 		setNotSelectedBorder();
 
+		// we only support tabs on top if we have FlatLaf because we can add a trailing component for our menu
+		boolean usingFlatLaf = tabs.getUI().getClass().getPackageName().startsWith("com.formdev.flatlaf");
+
 		// default to tabs on bottom. if we need to change it we will when the first dockable is added
-		tabs.setTabPlacement(JTabbedPane.BOTTOM);
+//		tabs.setTabPlacement(JTabbedPane.BOTTOM);
+		tabPlacement = topTabs && usingFlatLaf ? JTabbedPane.TOP : JTabbedPane.BOTTOM;
+		tabs.setTabPlacement(tabPlacement);
 
 		tabs.setTabLayoutPolicy(Settings.getTabLayoutPolicy());
 
-		if (Settings.alwaysDisplayTabsMode()) {
+		if (topTabs) {
 			configureTrailingComponent();
 		}
 
@@ -93,6 +105,10 @@ public DockedTabbedPanel(DockingAPI docking, DockableWrapper dockable) {
 		addPanel(dockable);
 	}
 
+	public DockedTabbedPanel(DockingAPI docking, DockableTabGroup group, DockableWrapper firstDockable) {
+		this(docking, firstDockable, group.getTabPlacement() == JTabbedPane.TOP);
+	}
+
 	public static void setSettingsIcon(Icon icon) {
 		settingsIcon = icon;
 	}
@@ -171,15 +187,14 @@ public void removeNotify() {
 	 * @param dockable The dockable to add
 	 */
 	public void addPanel(DockableWrapper dockable) {
-		// we only support tabs on top if we have FlatLaf because we can add a trailing component for our menu
-		boolean usingFlatLaf = tabs.getUI().getClass().getPackageName().startsWith("com.formdev.flatlaf");
 
-		if (Settings.alwaysDisplayTabsMode() && usingFlatLaf) {
-			tabs.setTabPlacement(JTabbedPane.TOP);
-		}
-		else {
-			tabs.setTabPlacement(JTabbedPane.BOTTOM);
-		}
+
+//		if (Settings.alwaysDisplayTabsMode() && usingFlatLaf) {
+//			tabs.setTabPlacement(JTabbedPane.TOP);
+//		}
+//		else {
+//			tabs.setTabPlacement(JTabbedPane.BOTTOM);
+//		}
 
 		panels.add(dockable);
 		tabs.add(dockable.getDockable().getTabText(), dockable.getDisplayPanel());

docking-api/src/ModernDocking/internal/DockingPanel.java

@@ -22,6 +22,7 @@ of this software and associated documentation files (the "Software"), to deal
 package ModernDocking.internal;
 
 import ModernDocking.Dockable;
+import ModernDocking.DockableTabGroup;
 import ModernDocking.DockingRegion;
 
 import javax.swing.*;
@@ -46,6 +47,8 @@ public abstract class DockingPanel extends JPanel {
 	 */
 	public abstract void dock(Dockable dockable, DockingRegion region, double dividerProportion);
 
+	public void dock(DockableTabGroup group, Dockable firstDockable, DockingRegion region, double dividerProportion) {}
+
 	/**
 	 * undock the given dockable, returns true if the dockable was found and removed
 	 *

docking-single-app/src/ModernDocking/Docking.java

@@ -285,6 +285,9 @@ public static void dock(Dockable source, Dockable target, DockingRegion region,
         instance.dock(source, target, region, dividerProportion);
     }
 
+    public static void dock(DockableTabGroup group, Dockable firstDockable, Dockable target, DockingRegion region) {
+        instance.dock(group, firstDockable, target, region);
+    }
     /**
      * create a new FloatingFrame window for the given dockable, undock it from its current frame (if there is one) and dock it into the new frame
      *