Fix the get owner DockingManagerWindow and Update drag and drop

source/Components/AvalonDock/Controls/DragService.cs

@@ -8,9 +8,11 @@ This program is provided to you under the terms of the Microsoft Public
  ************************************************************************/
 
 using AvalonDock.Layout;
+using System;
 using System.Collections.Generic;
 using System.Linq;
 using System.Windows;
+using System.Windows.Interop;
 
 namespace AvalonDock.Controls
 {
@@ -55,6 +57,7 @@ internal class DragService
 		private IOverlayWindow _currentWindow;
 		private List<IDropArea> _currentWindowAreas = new List<IDropArea>();
 		private IDropTarget _currentDropTarget;
+		private bool _isDrag;
 
 		#endregion fields
 
@@ -69,8 +72,6 @@ public DragService(LayoutFloatingWindowControl floatingWindow)
 		{
 			_floatingWindow = floatingWindow;
 			_manager = floatingWindow.Model.Root.Manager;
-
-			GetOverlayWindowHosts();
 		}
 
 		#endregion Constructors
@@ -87,6 +88,12 @@ internal void UpdateMouseLocation(Point dragPosition)
 			////var floatingWindowModel = _floatingWindow.Model as LayoutFloatingWindow;
 			// TODO - pass in without DPI adjustment, screen co-ords, adjust inside the target window
 
+			if (!_isDrag)
+			{
+				GetOverlayWindowHosts();
+				_isDrag = true;
+			}
+
 			var newHost = _overlayWindowHosts.FirstOrDefault(oh => oh.HitTestScreen(dragPosition));
 
 			if (_currentHost != null || _currentHost != newHost)
@@ -110,7 +117,11 @@ internal void UpdateMouseLocation(Point dragPosition)
 					if (_currentWindow != null)
 						_currentWindow.DragLeave(_floatingWindow);
 					if (_currentHost != null)
+					{
 						_currentHost.HideOverlayWindow();
+						GetOverlayWindowHosts();
+					}
+
 					_currentHost = null;
 				}
 
@@ -119,6 +130,25 @@ internal void UpdateMouseLocation(Point dragPosition)
 					_currentHost = newHost;
 					_currentWindow = _currentHost.ShowOverlayWindow(_floatingWindow);
 					_currentWindow.DragEnter(_floatingWindow);
+
+					// Set the target window to topmost
+					if (_currentHost is LayoutFloatingWindowControl fwc &&
+						(fwc.OwnedByDockingManagerWindow == _floatingWindow.OwnedByDockingManagerWindow || fwc.OwnedByDockingManagerWindow))
+					{
+						BringWindowToTop2(fwc);
+					}
+					else if (_currentHost is DockingManager dockingManager)
+					{
+						BringWindowToTop2(Window.GetWindow(dockingManager));
+					}
+
+					GetOverlayWindowHosts();
+
+					BringWindowToTop2(_floatingWindow);
+					if (_currentWindow is Window overlayWindow)
+					{
+						BringWindowToTop2(overlayWindow);
+					}
 				}
 			}
 
@@ -135,7 +165,6 @@ internal void UpdateMouseLocation(Point dragPosition)
 			List<IDropArea> areasToRemove = new List<IDropArea>();
 			_currentWindowAreas.ForEach(a =>
 			{
-
 				//is mouse still inside this area?
 				if (!a.DetectionRect.Contains(a.TransformToDeviceDPI(dragPosition)))
 				{
@@ -215,6 +244,7 @@ internal void Drop(Point dropLocation, out bool dropHandled)
 
 			_currentWindow = null;
 			_currentHost = null;
+			_isDrag = false;
 		}
 
 		/// <summary>
@@ -246,6 +276,12 @@ internal void Abort()
 
 		#region Private Methods
 
+		private void BringWindowToTop2(Window window)
+		{
+			Win32Helper.SetWindowPos(new WindowInteropHelper(window).Handle,
+				IntPtr.Zero, 0, 0, 0, 0, Win32Helper.SetWindowPosFlags.IgnoreResize | Win32Helper.SetWindowPosFlags.IgnoreMove | Win32Helper.SetWindowPosFlags.DoNotActivate);
+		}
+
 		/// <summary>
 		/// Adds <see cref="IOverlayWindowHost"/>s into a private collection of possible
 		/// drop target hosts that can show a drop target button to drop a dragged
@@ -256,14 +292,7 @@ private void GetOverlayWindowHosts()
 		{
 			if (_manager.Layout.RootPanel.CanDock)
 			{
-				// Add LayoutFloatingWindowControls as drop target hosts
-				// 1) Don't drop a floating window on to itself
-				// 2) Use this Drop target if its visible
-				_overlayWindowHosts.AddRange(_manager.GetFloatingWindowsByZOrder().OfType<LayoutAnchorableFloatingWindowControl>().Where(fw => fw != _floatingWindow && fw.IsVisible));
-				_overlayWindowHosts.AddRange(_manager.GetFloatingWindowsByZOrder().OfType<LayoutDocumentFloatingWindowControl>().Where(fw => fw != _floatingWindow && fw.IsVisible));
-
-				// Add dockingManager itself as a drop target host
-				_overlayWindowHosts.Add(_manager);
+				_manager.GetOverlayWindowHostsByZOrder(ref _overlayWindowHosts, _floatingWindow);
 			}
 		}
 

source/Components/AvalonDock/Controls/LayoutAnchorableFloatingWindowControl.cs

@@ -301,11 +301,9 @@ private void CreateOverlayWindow(LayoutFloatingWindowControl draggingWindow)
 
 			// Usually, the overlay window is made a child of the main window. However, if the floating
 			// window being dragged isn't also a child of the main window (because OwnedByDockingManagerWindow
-			// is set to false to allow the parent window to be minimized independently of floating windows),
-			// this causes the floating window to be moved behind the main window. Just not setting the parent
-			// seems to work acceptably here in that case.
+			// is set to false to allow the parent window to be minimized independently of floating windows)
 			if (draggingWindow?.OwnedByDockingManagerWindow ?? true)
-				_overlayWindow.Owner = Window.GetWindow(this);
+				_overlayWindow.Owner = Window.GetWindow(_model.Root.Manager);
 			else
 				_overlayWindow.Owner = null;
 

source/Components/AvalonDock/Controls/LayoutDocumentFloatingWindowControl.cs

@@ -16,7 +16,6 @@ This program is provided to you under the terms of the Microsoft Public
 using System.Windows;
 using System.Windows.Controls.Primitives;
 using System.Windows.Input;
-using System.Windows.Interop;
 
 namespace AvalonDock.Controls
 {
@@ -231,11 +230,9 @@ private void CreateOverlayWindow(LayoutFloatingWindowControl draggingWindow)
 
 			// Usually, the overlay window is made a child of the main window. However, if the floating
 			// window being dragged isn't also a child of the main window (because OwnedByDockingManagerWindow
-			// is set to false to allow the parent window to be minimized independently of floating windows),
-			// this causes the floating window to be moved behind the main window. Just not setting the parent
-			// seems to work acceptably here in that case.
+			// is set to false to allow the parent window to be minimized independently of floating windows)
 			if (draggingWindow?.OwnedByDockingManagerWindow ?? true)
-				_overlayWindow.Owner = Window.GetWindow(this);
+				_overlayWindow.Owner = Window.GetWindow(_model.Root.Manager);
 			else
 				_overlayWindow.Owner = null;
 

source/Components/AvalonDock/Controls/LayoutFloatingWindowControl.cs

@@ -52,7 +52,7 @@ public abstract class LayoutFloatingWindowControl : Window, ILayoutControl
 		/// </summary>
 		/// <see cref="TotalMargin"/>
 		private bool _isTotalMarginSet = false;
-
+		
 		#endregion fields
 
 		#region Constructors

source/Components/AvalonDock/DockingManager.cs

@@ -1621,7 +1621,7 @@ internal UIElement CreateUIElementForModel(ILayoutElement model)
 				{
 					//Owner = Window.GetWindow(this)
 				};
-				
+
 				newFW.UpdateOwnership();
 
 				// Fill list before calling Show (issue #254)
@@ -1665,7 +1665,7 @@ internal UIElement CreateUIElementForModel(ILayoutElement model)
 				{
 					//Owner = Window.GetWindow(this)
 				};
-				
+
 				newFW.UpdateOwnership();
 
 				// Fill list before calling Show (issue #254)
@@ -1777,6 +1777,44 @@ internal IEnumerable<LayoutFloatingWindowControl> GetFloatingWindowsByZOrder()
 			}
 		}
 
+		internal void GetOverlayWindowHostsByZOrder(ref List<IOverlayWindowHost> overlayWindowHosts, LayoutFloatingWindowControl dragFloatingWindow)
+		{
+			overlayWindowHosts.Clear();
+
+			var topFloatingWindows = new List<IOverlayWindowHost>();
+			var bottomFloatingWindows = new List<IOverlayWindowHost>();
+
+			var parentWindow = Window.GetWindow(this);
+			var windowParentHandle = parentWindow != null ? new WindowInteropHelper(parentWindow).Handle : Process.GetCurrentProcess().MainWindowHandle;
+			var b = Win32Helper.GetWindowZOrder(windowParentHandle, out var mainWindow_z);
+			var currentHandle = Win32Helper.GetWindow(windowParentHandle, (uint)Win32Helper.GetWindow_Cmd.GW_HWNDFIRST);
+			while (currentHandle != IntPtr.Zero)
+			{
+				for (int i = 0; i < _fwList.Count; i++)
+				{
+					var fw = _fwList[i];
+					if (fw is IOverlayWindowHost host && fw != dragFloatingWindow && fw.IsVisible)
+					{
+						var fw_hwnd = new WindowInteropHelper(fw).Handle;
+						if (currentHandle == fw_hwnd && fw.Model.Root != null && fw.Model.Root.Manager == this)
+						{
+							if (fw.OwnedByDockingManagerWindow || (Win32Helper.GetWindowZOrder(fw_hwnd, out var fw_z) && fw_z > mainWindow_z))
+								topFloatingWindows.Add(host);
+							else
+								bottomFloatingWindows.Add(host);
+							break;
+						}
+					}
+				}
+
+				currentHandle = Win32Helper.GetWindow(currentHandle, (uint)Win32Helper.GetWindow_Cmd.GW_HWNDNEXT);
+			}
+
+			overlayWindowHosts.AddRange(topFloatingWindows);
+			overlayWindowHosts.Add(this);
+			overlayWindowHosts.AddRange(bottomFloatingWindows);
+		}
+
 		internal void RemoveFloatingWindow(LayoutFloatingWindowControl floatingWindow) => _fwList.Remove(floatingWindow);
 
 		internal void ExecuteCloseCommand(LayoutDocument document)
@@ -2104,9 +2142,7 @@ private void CreateOverlayWindow(LayoutFloatingWindowControl draggingWindow = nu
 
 			// Usually, the overlay window is made a child of the main window. However, if the floating
 			// window being dragged isn't also a child of the main window (because OwnedByDockingManagerWindow
-			// is set to false to allow the parent window to be minimized independently of floating windows),
-			// this causes the floating window to be moved behind the main window. Just not setting the parent
-			// seems to work acceptably here in that case.
+			// is set to false to allow the parent window to be minimized independently of floating windows)
 			if (draggingWindow?.OwnedByDockingManagerWindow ?? true)
 				_overlayWindow.Owner = Window.GetWindow(this);
 			else

source/Components/AvalonDock/Win32Helper.cs

@@ -323,9 +323,6 @@ internal static RECT GetWindowRect(IntPtr hWnd)
 		[DllImport("user32.dll")]
 		internal static extern IntPtr GetTopWindow(IntPtr hWnd);
 
-		internal const uint GW_HWNDNEXT = 2;
-		internal const uint GW_HWNDPREV = 3;
-
 		[DllImport("user32.dll", SetLastError = true)]
 		internal static extern IntPtr GetWindow(IntPtr hWnd, uint uCmd);
 
@@ -340,6 +337,28 @@ internal enum GetWindow_Cmd : uint
 			GW_ENABLEDPOPUP = 6
 		}
 
+		public static bool GetWindowZOrder(IntPtr hwnd, out int zOrder)
+		{
+			var lowestHwnd = GetWindow(hwnd, (uint)GetWindow_Cmd.GW_HWNDLAST);
+
+			var z = 0;
+			var hwndTmp = lowestHwnd;
+			while (hwndTmp != IntPtr.Zero)
+			{
+				if (hwnd == hwndTmp)
+				{
+					zOrder = z;
+					return true;
+				}
+
+				hwndTmp = GetWindow(hwndTmp, (uint)GetWindow_Cmd.GW_HWNDPREV);
+				z++;
+			}
+
+			zOrder = int.MinValue;
+			return false;
+		}
+
 		internal static int MakeLParam(int LoWord, int HiWord)
 		{
 			return (int)((HiWord << 16) | (LoWord & 0xffff));