Fixes for taskbar app

Interop/X11.cs

@@ -88,6 +88,9 @@ internal static partial class X11
     [LibraryImport(LibX11, StringMarshalling = StringMarshalling.Utf8)]
     public static partial int XStoreName(IntPtr display, IntPtr window, string windowName);
 
+    [LibraryImport(LibX11)]
+    public static partial int XSetClassHint(IntPtr display, IntPtr window, ref XClassHint classHint);
+
     [LibraryImport(LibX11)]
     public static partial int XRaiseWindow(IntPtr display, IntPtr window);
 

Interop/XClassHint.cs

@@ -0,0 +1,13 @@
+// Licensed to the .NET Foundation under one or more agreements.
+// The .NET Foundation licenses this file to you under the MIT license.
+
+using System.Runtime.InteropServices;
+
+namespace Microsoft.Maui.Platform.Linux.Interop;
+
+[StructLayout(LayoutKind.Sequential)]
+public struct XClassHint
+{
+    public IntPtr res_name;
+    public IntPtr res_class;
+}