Bug 540841: [GTK4] Rename GdkWindow to GdkSurface

Fix compile warning.

Change-Id: I4602a98d98c31437791eb7aace8d77548a3a26c7
Signed-off-by: Alexander Kurtakov <akurtako@redhat.com>
diff --git a/bundles/org.eclipse.swt/Eclipse SWT/gtk/org/eclipse/swt/widgets/Shell.java b/bundles/org.eclipse.swt/Eclipse SWT/gtk/org/eclipse/swt/widgets/Shell.java
index 7ea1c5f..b239ee4 100644
--- a/bundles/org.eclipse.swt/Eclipse SWT/gtk/org/eclipse/swt/widgets/Shell.java
+++ b/bundles/org.eclipse.swt/Eclipse SWT/gtk/org/eclipse/swt/widgets/Shell.java
@@ -2086,7 +2086,6 @@
 			long /*int*/ surface = gtk_widget_get_surface (parentHandle);
 			Rectangle rect = getBoundsInPixels ();
 			GdkRectangle gdkRectangle = new GdkRectangle ();
-			GdkWindowAttr attributes = new GdkWindowAttr ();
 			gdkRectangle.width = rect.width;
 			gdkRectangle.height = rect.height;
 			enableSurface = GDK.gdk_surface_new_child (surface, gdkRectangle);