Revert of the change to the DWMWINDOWATTRIBUTE, as the enum values were not fixed we lost some functionality. Also fixed some potential issues with the ThumbnailForm, and aligned a bit of code with Dapplo.Window [skip ci]

Greenshot/Forms/MainForm.cs

@@ -918,7 +918,7 @@ namespace Greenshot.Forms {
 
 		private void ShowThumbnailOnEnter(object sender, EventArgs e) {
             if (sender is not ToolStripMenuItem captureWindowItem) return;
-            WindowDetails window = captureWindowItem.Tag as WindowDetails;
+            var window = captureWindowItem.Tag as WindowDetails;
             if (_thumbnailForm == null) {
                 _thumbnailForm = new ThumbnailForm();
             }
@@ -939,29 +939,39 @@ namespace Greenshot.Forms {
 			_thumbnailForm = null;
 		}
 
+        /// <summary>
+        /// Create the "capture window from list" list
+        /// </summary>
+        /// <param name="menuItem">ToolStripMenuItem</param>
+        /// <param name="eventHandler">EventHandler</param>
 		public void AddCaptureWindowMenuItems(ToolStripMenuItem menuItem, EventHandler eventHandler) {
 			menuItem.DropDownItems.Clear();
 			// check if thumbnailPreview is enabled and DWM is enabled
 			bool thumbnailPreview = _conf.ThumnailPreview && DWM.IsDwmEnabled;
 
-			foreach(WindowDetails window in WindowDetails.GetTopLevelWindows()) {
+			foreach(var window in WindowDetails.GetTopLevelWindows()) {
-
+                if (LOG.IsDebugEnabled)
+                {
+                    LOG.Debug(window.ToString());
+                }
 				string title = window.Text;
-				if (title != null) {
+                if (string.IsNullOrEmpty(title))
-					if (title.Length > _conf.MaxMenuItemLength) {
+                {
-						title = title.Substring(0, Math.Min(title.Length, _conf.MaxMenuItemLength));
+                    continue;
-					}
+                }
-					ToolStripItem captureWindowItem = menuItem.DropDownItems.Add(title);
+                if (title.Length > _conf.MaxMenuItemLength) {
-					captureWindowItem.Tag = window;
+                    title = title.Substring(0, Math.Min(title.Length, _conf.MaxMenuItemLength));
-					captureWindowItem.Image = window.DisplayIcon;
+                }
-					captureWindowItem.Click += eventHandler;
+                ToolStripItem captureWindowItem = menuItem.DropDownItems.Add(title);
-					// Only show preview when enabled
+                captureWindowItem.Tag = window;
-					if (thumbnailPreview) {
+                captureWindowItem.Image = window.DisplayIcon;
-						captureWindowItem.MouseEnter += ShowThumbnailOnEnter;
+                captureWindowItem.Click += eventHandler;
-						captureWindowItem.MouseLeave += HideThumbnailOnLeave;
+                // Only show preview when enabled
-					}
+                if (thumbnailPreview) {
-				}
+                    captureWindowItem.MouseEnter += ShowThumbnailOnEnter;
-			}
+                    captureWindowItem.MouseLeave += HideThumbnailOnLeave;
+                }
+            }
 		}
 
 		private void CaptureAreaToolStripMenuItemClick(object sender, EventArgs e) {

Greenshot/Helpers/CaptureHelper.cs

@@ -970,7 +970,7 @@ namespace Greenshot.Helpers {
             // The following, to be precise the HideApp, causes the app to close as described in BUG-1620
 			// Added check for metro (Modern UI) apps, which might be maximized and cover the screen.
 
-			//foreach(WindowDetails app in WindowDetails.GetMetroApps()) {
+			//foreach(WindowDetails app in WindowDetails.GetAppWindows()) {
 			//	if (app.Maximised) {
 			//		app.HideApp();
 			//	}

GreenshotPlugin/Controls/ThumbnailForm.cs

@@ -22,6 +22,7 @@ using System;
 using System.Windows.Forms;
 using GreenshotPlugin.Core;
 using System.Drawing;
+using GreenshotPlugin.Core.Enums;
 using GreenshotPlugin.IniFile;
 using GreenshotPlugin.UnmanagedHelpers;
 using GreenshotPlugin.UnmanagedHelpers.Enums;
@@ -32,7 +33,7 @@ namespace GreenshotPlugin.Controls {
 	/// This form allows us to show a Thumbnail preview of a window near the context menu when selecting a window to capture.
 	/// Didn't make it completely "generic" yet, but at least most logic is in here so we don't have it in the mainform.
 	/// </summary>
-	public class ThumbnailForm : FormWithoutActivation {
+	public sealed class ThumbnailForm : FormWithoutActivation {
 		private static readonly CoreConfiguration conf = IniConfig.GetIniSection<CoreConfiguration>();
 
 		private IntPtr _thumbnailHandle = IntPtr.Zero;
@@ -59,12 +60,13 @@ namespace GreenshotPlugin.Controls {
 			base.Hide();
 		}
 
-		private void UnregisterThumbnail() {
+		private void UnregisterThumbnail()
-			if (_thumbnailHandle != IntPtr.Zero) {
+        {
-				DWM.DwmUnregisterThumbnail(_thumbnailHandle);
+            if (_thumbnailHandle == IntPtr.Zero) return;
-				_thumbnailHandle = IntPtr.Zero;
+
-			}
+            DWM.DwmUnregisterThumbnail(_thumbnailHandle);
-		}
+            _thumbnailHandle = IntPtr.Zero;
+        }
 
 		/// <summary>
 		/// Show the thumbnail of the supplied window above (or under) the parent Control
@@ -75,41 +77,60 @@ namespace GreenshotPlugin.Controls {
 			UnregisterThumbnail();
 
 			DWM.DwmRegisterThumbnail(Handle, window.Handle, out _thumbnailHandle);
-			if (_thumbnailHandle != IntPtr.Zero) {
+            if (_thumbnailHandle == IntPtr.Zero) return;
-                DWM.DwmQueryThumbnailSourceSize(_thumbnailHandle, out var sourceSize);
-				int thumbnailHeight = 200;
-				int thumbnailWidth = (int)(thumbnailHeight * (sourceSize.Width / (float)sourceSize.Height));
-				if (parentControl != null && thumbnailWidth > parentControl.Width) {
-					thumbnailWidth = parentControl.Width;
-					thumbnailHeight = (int)(thumbnailWidth * (sourceSize.Height / (float)sourceSize.Width));
-				}
-				Width = thumbnailWidth;
-				Height = thumbnailHeight;
-				// Prepare the displaying of the Thumbnail
-				DWM_THUMBNAIL_PROPERTIES props = new DWM_THUMBNAIL_PROPERTIES
-				{
-					Opacity = 255,
-					Visible = true,
-					SourceClientAreaOnly = false,
-					Destination = new RECT(0, 0, thumbnailWidth, thumbnailHeight)
-				};
-				DWM.DwmUpdateThumbnailProperties(_thumbnailHandle, ref props);
-				if (parentControl != null) {
-					AlignToControl(parentControl);
-				}
 
-				if (!Visible) {
+            var result = DWM.DwmQueryThumbnailSourceSize(_thumbnailHandle, out var sourceSize);
-					Show();
+            if (result.Failed())
-				}
+            {
-				// Make sure it's on "top"!
+                DWM.DwmUnregisterThumbnail(_thumbnailHandle);
-				if (parentControl != null) {
+                return;
-					User32.SetWindowPos(Handle, parentControl.Handle, 0, 0, 0, 0, WindowPos.SWP_NOMOVE | WindowPos.SWP_NOSIZE | WindowPos.SWP_NOACTIVATE);
+            }
-				}
+
-			}
+            if (sourceSize.IsEmpty)
-		}
+            {
+                DWM.DwmUnregisterThumbnail(_thumbnailHandle);
+                return;
+            }
+
+            int thumbnailHeight = 200;
+            int thumbnailWidth = (int)(thumbnailHeight * (sourceSize.Width / (float)sourceSize.Height));
+            if (parentControl != null && thumbnailWidth > parentControl.Width)
+            {
+                thumbnailWidth = parentControl.Width;
+                thumbnailHeight = (int)(thumbnailWidth * (sourceSize.Height / (float)sourceSize.Width));
+            }
+            Width = thumbnailWidth;
+            Height = thumbnailHeight;
+            // Prepare the displaying of the Thumbnail
+            var dwmThumbnailProperties = new DWM_THUMBNAIL_PROPERTIES
+            {
+                Opacity = 255,
+                Visible = true,
+                SourceClientAreaOnly = false,
+                Destination = new RECT(0, 0, thumbnailWidth, thumbnailHeight)
+            };
+            result = DWM.DwmUpdateThumbnailProperties(_thumbnailHandle, ref dwmThumbnailProperties);
+            if (result.Failed())
+            {
+                DWM.DwmUnregisterThumbnail(_thumbnailHandle);
+                return;
+            }
+
+            if (parentControl != null) {
+                AlignToControl(parentControl);
+            }
+
+            if (!Visible) {
+                Show();
+            }
+            // Make sure it's on "top"!
+            if (parentControl != null) {
+                User32.SetWindowPos(Handle, parentControl.Handle, 0, 0, 0, 0, WindowPos.SWP_NOMOVE | WindowPos.SWP_NOSIZE | WindowPos.SWP_NOACTIVATE);
+            }
+        }
 
 		public void AlignToControl(Control alignTo) {
-			Rectangle screenBounds = WindowCapture.GetScreenBounds();
+			var screenBounds = WindowCapture.GetScreenBounds();
 			if (screenBounds.Contains(alignTo.Left, alignTo.Top - Height)) {
 				Location = new Point(alignTo.Left + (alignTo.Width / 2) - (Width / 2), alignTo.Top - Height);
 			} else {

GreenshotPlugin/Core/WindowDetails.cs

@@ -2,7 +2,9 @@
 using System.Collections.Generic;
 using System.Diagnostics;
 using System.Drawing;
+using System.Drawing.Drawing2D;
 using System.Drawing.Imaging;
+using System.Linq;
 using System.Runtime.InteropServices;
 using System.Text;
 using System.Text.RegularExpressions;
@@ -25,11 +27,11 @@ namespace GreenshotPlugin.Core
     ///
     /// Provides details about a Window returned by the  enumeration
     /// </summary>
-    public class WindowDetails : IEquatable<WindowDetails>{
+    public class WindowDetails : IEquatable<WindowDetails> {
-        private const string MetroWindowsClass = "Windows.UI.Core.CoreWindow"; //Used for Windows 8(.1)
+        private const string AppWindowClass = "Windows.UI.Core.CoreWindow"; //Used for Windows 8(.1)
-        private const string FramedAppClass = "ApplicationFrameWindow"; // Windows 10 uses ApplicationFrameWindow
+        private const string AppFrameWindowClass = "ApplicationFrameWindow"; // Windows 10 uses ApplicationFrameWindow
-        private const string MetroApplauncherClass = "ImmersiveLauncher";
+        private const string ApplauncherClass = "ImmersiveLauncher";
-        private const string MetroGutterClass = "ImmersiveGutter";
+        private const string GutterClass = "ImmersiveGutter";
         private static readonly IList<string> IgnoreClasses = new List<string>(new[] { "Progman", "Button", "Dwm" }); //"MS-SDIa"
 
         private static readonly ILog Log = LogManager.GetLogger(typeof(WindowDetails));
@@ -72,23 +74,28 @@ namespace GreenshotPlugin.Core
         /// This checks if the window is a Windows 8 App
         /// For Windows 10 most normal code works, as it's hosted inside "ApplicationFrameWindow"
         /// </summary>
-        public bool IsApp => MetroWindowsClass.Equals(ClassName);
+        public bool IsApp => AppWindowClass.Equals(ClassName);
 
         /// <summary>
         /// This checks if the window is a Windows 10 App
         /// For Windows 10 apps are hosted inside "ApplicationFrameWindow"
         /// </summary>
-        public bool IsWin10App => FramedAppClass.Equals(ClassName);
+        public bool IsWin10App => AppFrameWindowClass.Equals(ClassName);
 
+        /// <summary>
+        /// Check if this window belongs to a background app
+        /// </summary>
+        public bool IsBackgroundWin10App => WindowsVersion.IsWindows10OrLater && AppFrameWindowClass.Equals(ClassName) && !Children.Any(window => string.Equals(window.ClassName, AppWindowClass));
+    
         /// <summary>
         /// Check if the window is the metro gutter (sizeable separator)
         /// </summary>
-        public bool IsGutter => MetroGutterClass.Equals(ClassName);
+        public bool IsGutter => GutterClass.Equals(ClassName);
 
         /// <summary>
         /// Test if this window is for the App-Launcher
         /// </summary>
-        public bool IsAppLauncher => MetroApplauncherClass.Equals(ClassName);
+        public bool IsAppLauncher => ApplauncherClass.Equals(ClassName);
 
         /// <summary>
         /// Check if this window is the window of a metro app
@@ -447,7 +454,7 @@ namespace GreenshotPlugin.Core
         /// </summary>
         public bool Visible {
             get {
-                // Tip from Raymond Chen
+                // Tip from Raymond Chen https://devblogs.microsoft.com/oldnewthing/20200302-00/?p=103507
                 if (IsCloaked)
                 {
                     return false;
@@ -1337,7 +1344,7 @@ namespace GreenshotPlugin.Core
         /// <returns>List WindowDetails with all the visible top level windows</returns>
         public static IEnumerable<WindowDetails> GetVisibleWindows() {
             Rectangle screenBounds = WindowCapture.GetScreenBounds();
-            foreach(var window in GetMetroApps()) {
+            foreach(var window in GetAppWindows()) {
                 if (IsVisible(window, screenBounds))
                 {
                     yield return window;
@@ -1357,37 +1364,24 @@ namespace GreenshotPlugin.Core
         /// These are all Windows with Classname "Windows.UI.Core.CoreWindow"
         /// </summary>
         /// <returns>List WindowDetails with visible metro apps</returns>
-        public static IEnumerable<WindowDetails> GetMetroApps() {
+        public static IEnumerable<WindowDetails> GetAppWindows() {
             // if the appVisibility != null we have Windows 8.
             if (AppVisibility == null)
             {
                 yield break;
             }
-            //string[] wcs = {"ImmersiveGutter", "Snapped Desktop", "ImmersiveBackgroundWindow","ImmersiveLauncher","Windows.UI.Core.CoreWindow","ApplicationManager_ImmersiveShellWindow","SearchPane","MetroGhostWindow","EdgeUiInputWndClass", "NativeHWNDHost", "Shell_CharmWindow"};
+            var nextHandle = User32.FindWindow(AppWindowClass, null);
-            //List<WindowDetails> specials = new List<WindowDetails>();
-            //foreach(string wc in wcs) {
-            //	IntPtr wcHandle = User32.FindWindow(null, null);
-            //	while (wcHandle != IntPtr.Zero) {
-            //		WindowDetails special = new WindowDetails(wcHandle);
-            //		if (special.WindowRectangle.Left >= 1920 && special.WindowRectangle.Size != Size.Empty) {
-            //			specials.Add(special);
-            //			LOG.DebugFormat("Found special {0} : {1} at {2} visible: {3} {4} {5}", special.ClassName, special.Text, special.WindowRectangle, special.Visible, special.ExtendedWindowStyle, special.WindowStyle);
-            //		}
-            //		wcHandle = User32.FindWindowEx(IntPtr.Zero, wcHandle, null, null);
-            //	};
-            //}
-            IntPtr nextHandle = User32.FindWindow(MetroWindowsClass, null);
             while (nextHandle != IntPtr.Zero) {
                 var metroApp = new WindowDetails(nextHandle);
                 yield return metroApp;
                 // Check if we have a gutter!
                 if (metroApp.Visible && !metroApp.Maximised) {
-                    var gutterHandle = User32.FindWindow(MetroGutterClass, null);
+                    var gutterHandle = User32.FindWindow(GutterClass, null);
                     if (gutterHandle != IntPtr.Zero) {
                         yield return new WindowDetails(gutterHandle);
                     }
                 }
-                nextHandle = User32.FindWindowEx(IntPtr.Zero, nextHandle, MetroWindowsClass, null);
+                nextHandle = User32.FindWindowEx(IntPtr.Zero, nextHandle, AppWindowClass, null);
             }
         }
 
@@ -1398,21 +1392,10 @@ namespace GreenshotPlugin.Core
         /// <returns>bool</returns>
         private static bool IsTopLevel(WindowDetails window)
         {
-            // Window is not on this desktop
             if (window.IsCloaked)
             {
                 return false;
             }
-
-            // Ignore windows without title
-            if (window.Text.Length == 0)
-            {
-                return false;
-            }
-            if (IgnoreClasses.Contains(window.ClassName))
-            {
-                return false;
-            }
             // Windows without size
             if (window.WindowRectangle.Size.Width * window.WindowRectangle.Size.Height == 0)
             {
@@ -1437,7 +1420,21 @@ namespace GreenshotPlugin.Core
             {
                 return false;
             }
-            return window.Visible || window.Iconic;
+            // Ignore windows without title
+            if (window.Text.Length == 0)
+            {
+                return false;
+            }
+            if (IgnoreClasses.Contains(window.ClassName))
+            {
+                return false;
+            }
+            if (!(window.Visible || window.Iconic))
+            {
+                return false;
+            }
+
+            return !window.IsBackgroundWin10App;
         }
 
         /// <summary>
@@ -1445,7 +1442,7 @@ namespace GreenshotPlugin.Core
         /// </summary>
         /// <returns>List WindowDetails with all the top level windows</returns>
         public static IEnumerable<WindowDetails> GetTopLevelWindows() {
-            foreach (var possibleTopLevel in GetMetroApps())
+            foreach (var possibleTopLevel in GetAppWindows())
             {
                 if (IsTopLevel(possibleTopLevel))
                 {
@@ -1523,7 +1520,7 @@ namespace GreenshotPlugin.Core
             if (AppVisibility == null) {
                 return null;
             }
-            IntPtr appLauncher = User32.FindWindow(MetroApplauncherClass, null);
+            IntPtr appLauncher = User32.FindWindow(ApplauncherClass, null);
             if (appLauncher != IntPtr.Zero) {
                 return new WindowDetails (appLauncher);
             }
@@ -1542,5 +1539,32 @@ namespace GreenshotPlugin.Core
                 return false;
             }
         }
+
+        /// <summary>
+        /// Make a string representation of the window details
+        /// </summary>
+        /// <returns>string</returns>
+        public override string ToString()
+        {
+            var result = new StringBuilder();
+            result.AppendLine($"Text: {Text}");
+            result.AppendLine($"ClassName: {ClassName}");
+            result.AppendLine($"ExtendedWindowStyle: {ExtendedWindowStyle}");
+            result.AppendLine($"WindowStyle: {WindowStyle}");
+            result.AppendLine($"Size: {WindowRectangle.Size}");
+            result.AppendLine($"HasParent: {HasParent}");
+            result.AppendLine($"IsWin10App: {IsWin10App}");
+            result.AppendLine($"IsApp: {IsApp}");
+            result.AppendLine($"Visible: {Visible}");
+            result.AppendLine($"IsWindowVisible: {User32.IsWindowVisible(Handle)}");
+            result.AppendLine($"IsCloaked: {IsCloaked}");
+            result.AppendLine($"Iconic: {Iconic}");
+            result.AppendLine($"IsBackgroundWin10App: {IsBackgroundWin10App}");
+            if (HasChildren)
+            {
+                result.AppendLine($"Children classes: {string.Join(",", Children.Select(c => c.ClassName))}");
+            }
+            return result.ToString();
+        }
     }
 }

GreenshotPlugin/UnmanagedHelpers/DWM.cs

@@ -23,6 +23,7 @@ using System;
 using System.Drawing;
 using System.Runtime.InteropServices;
 using GreenshotPlugin.Core;
+using GreenshotPlugin.Core.Enums;
 using GreenshotPlugin.UnmanagedHelpers.Enums;
 using GreenshotPlugin.UnmanagedHelpers.Structs;
 using Microsoft.Win32;
@@ -40,9 +41,9 @@ namespace GreenshotPlugin.UnmanagedHelpers {
 		[DllImport("dwmapi", SetLastError = true)]
 		public static extern int DwmUnregisterThumbnail(IntPtr thumb);
 		[DllImport("dwmapi", SetLastError = true)]
-		public static extern int DwmQueryThumbnailSourceSize(IntPtr thumb, out SIZE size);
+		public static extern HResult DwmQueryThumbnailSourceSize(IntPtr thumb, out SIZE size);
 		[DllImport("dwmapi", SetLastError = true)]
-		public static extern int DwmUpdateThumbnailProperties(IntPtr hThumb, ref DWM_THUMBNAIL_PROPERTIES props);
+		public static extern HResult DwmUpdateThumbnailProperties(IntPtr hThumb, ref DWM_THUMBNAIL_PROPERTIES props);
 
 		// Deprecated as of Windows 8 Release Preview
 		[DllImport("dwmapi", SetLastError = true)]

GreenshotPlugin/UnmanagedHelpers/Enums/DWMWINDOWATTRIBUTE.cs

@@ -26,7 +26,21 @@ namespace GreenshotPlugin.UnmanagedHelpers.Enums
     [SuppressMessage("ReSharper", "InconsistentNaming")]
     public enum DWMWINDOWATTRIBUTE : uint
     {
+        DWMWA_NCRENDERING_ENABLED = 1,
+        DWMWA_NCRENDERING_POLICY,
+        DWMWA_TRANSITIONS_FORCEDISABLED,
+        DWMWA_ALLOW_NCPAINT,
+        DWMWA_CAPTION_BUTTON_BOUNDS,
+        DWMWA_NONCLIENT_RTL_LAYOUT,
+        DWMWA_FORCE_ICONIC_REPRESENTATION,
+        DWMWA_FLIP3D_POLICY,
         DWMWA_EXTENDED_FRAME_BOUNDS, // This is the one we need for retrieving the Window size since Windows Vista
+        DWMWA_HAS_ICONIC_BITMAP,        // Since Windows 7
+        DWMWA_DISALLOW_PEEK,            // Since Windows 7
+        DWMWA_EXCLUDED_FROM_PEEK,       // Since Windows 7
+        DWMWA_CLOAK,                    // Since Windows 8
         DWMWA_CLOAKED,                  // Since Windows 8
+        DWMWA_FREEZE_REPRESENTATION,    // Since Windows 8
+        DWMWA_LAST
     }
 }

GreenshotPlugin/UnmanagedHelpers/Structs/SIZE.cs

@@ -40,5 +40,7 @@ namespace GreenshotPlugin.UnmanagedHelpers.Structs {
 		public Size ToSize() {
 			return new Size(Width, Height);
 		}
+
+		public bool IsEmpty => Width * Height == 0;
 	}
 }