[GTK3] Lock and sync X11 display

src/Gtk/Avalonia.Gtk3/FramebufferManager.cs

@@ -40,7 +40,7 @@ namespace Avalonia.Gtk3
             return new ImageSurfaceFramebuffer(_window, width, height, _window.LastKnownScaleFactor);
         }
 
-        private static int X11ErrorHandler(IntPtr d, IntPtr e)
+        private static int X11ErrorHandler(IntPtr d, ref X11.XErrorEvent e)
         {
             return 0;
         }

src/Gtk/Avalonia.Gtk3/Gtk3Platform.cs

@@ -30,6 +30,10 @@ namespace Avalonia.Gtk3
         {
             if (!s_gtkInitialized)
             {
+                try
+                {
+                    X11.XInitThreads();
+                }catch{}
                 Resolver.Resolve();
                 Native.GtkInit(0, IntPtr.Zero);
                 var disp = Native.GdkGetDefaultDisplay();

src/Gtk/Avalonia.Gtk3/X11.cs

@@ -5,9 +5,18 @@ namespace Avalonia.Gtk3
 {
     class X11
     {
+        [DllImport("libX11.so.6")]
+        public static extern IntPtr XInitThreads();
+        
         [DllImport("libX11.so.6")]
         public static extern IntPtr XOpenDisplay(IntPtr name);
         
+        [DllImport("libX11.so.6")]
+        public static extern IntPtr XLockDisplay(IntPtr display);
+        
+        [DllImport("libX11.so.6")]
+        public static extern IntPtr XUnlockDisplay(IntPtr display);
+        
         [DllImport("libX11.so.6")]
         public static extern IntPtr XFreeGC(IntPtr display, IntPtr gc);
         
@@ -23,13 +32,28 @@ namespace Avalonia.Gtk3
         [DllImport("libX11.so.6")]
         public static extern IntPtr XSetErrorHandler(XErrorHandler handler);
 
-        public delegate int XErrorHandler(IntPtr display, IntPtr error);
+        [DllImport("libX11.so.6")]
+        public static extern int XSync(IntPtr display, bool discard);
+
+        public delegate int XErrorHandler(IntPtr display, ref XErrorEvent error);
 
         [DllImport("libX11.so.6")]
         public static extern int XPutImage(IntPtr display, IntPtr drawable, IntPtr gc, ref XImage image,
             int srcx, int srcy, int destx, int desty, uint width, uint height);
 
-        
+        [StructLayout(LayoutKind.Sequential)]
+        public unsafe struct XErrorEvent
+        {
+            public int type;
+            public IntPtr* display; /* Display the event was read from */
+            public ulong serial; /* serial number of failed request */
+            public byte error_code; /* error code of failed request */
+            public byte request_code; /* Major op-code of failed request */
+            public byte minor_code; /* Minor op-code of failed request */
+            public IntPtr resourceid; /* resource id */
+        }
+
+        [StructLayout(LayoutKind.Sequential)]
         public unsafe struct XImage
         {
             public int width, height; /* size of image */

src/Gtk/Avalonia.Gtk3/X11Framebuffer.cs

@@ -38,10 +38,13 @@ namespace Avalonia.Gtk3
             image.depth = 24;
             image.bytes_per_line = RowBytes - Width * 4;
             image.bits_per_pixel = bitsPerPixel;
+            X11.XLockDisplay(_display);
             X11.XInitImage(ref image);
             var gc = X11.XCreateGC(_display, _xid, 0, IntPtr.Zero);
             X11.XPutImage(_display, _xid, gc, ref image, 0, 0, 0, 0, (uint) Width, (uint) Height);
             X11.XFreeGC(_display, gc);
+            X11.XSync(_display, true);
+            X11.XUnlockDisplay(_display);
             _blob.Dispose();
         }