Fix/drag and drop on linux

.gitignore

@@ -219,3 +219,4 @@ src/Browser/Avalonia.Browser.Blazor/wwwroot
 src/Browser/Avalonia.Browser/wwwroot
 api/diff
 src/Browser/Avalonia.Browser/staticwebassets
+/.nuke/temp/dotnet-win/host/fxr/8.0.11/hostfxr.dll

src/Avalonia.X11/DragNDrop/DragDropEffectsExtensions.cs

@@ -0,0 +1,32 @@
+using System;
+using Avalonia.Input;
+
+namespace Avalonia.X11
+{
+    internal static class DragDropEffectsExtensions
+    {
+        public static DragDropEffects ConvertDropEffect(this X11Atoms atoms, IntPtr effect)
+        {
+            DragDropEffects result = DragDropEffects.None;
+            if (((uint)effect & (uint)(atoms.XdndActionCopy)) == (uint)atoms.XdndActionCopy)
+                result |= DragDropEffects.Copy;
+            if (((uint)effect & (uint)(atoms.XdndActionMove)) == (uint)atoms.XdndActionMove)
+                result |= DragDropEffects.Move;
+            if (((uint)effect & (uint)(atoms.XdndActionLink)) == (uint)atoms.XdndActionLink)
+                result |= DragDropEffects.Link;
+            return result; 
+        }       
+
+        public static IntPtr ConvertDropEffect(this X11Atoms atoms, DragDropEffects operation)
+        {
+            uint result = (uint)IntPtr.Zero;
+            if (operation.HasAllFlags(DragDropEffects.Copy))
+                result |= (uint)atoms.XdndActionCopy;
+            if (operation.HasAllFlags(DragDropEffects.Move))
+                result |= (uint)atoms.XdndActionMove;
+            if (operation.HasAllFlags(DragDropEffects.Link))
+                result |= (uint)atoms.XdndActionLink;
+            return (IntPtr)result;
+        }
+    }
+}