diff -r 28bd481113cc glass/glass-mat-lib-gtk/src/com/sun/glass/ui/GlassApplication.cpp
--- a/glass/glass-mat-lib-gtk/src/com/sun/glass/ui/GlassApplication.cpp	Tue May 15 18:29:44 2012 -0400
+++ b/glass/glass-mat-lib-gtk/src/com/sun/glass/ui/GlassApplication.cpp	Sun May 13 09:13:06 2012 -0400
@@ -265,6 +265,11 @@
 JNIEXPORT void JNICALL Java_com_sun_glass_ui_gtk_GtkApplication_enterNestedEventLoopImpl
   (JNIEnv * env, jobject obj)
 {
+    // GTK installs its own X error handler that conflicts with AWT.
+    // During drag and drop, AWT hides errors so hide them for here.
+    // A better solution would be to save and restore the X handler.
+    gdk_error_trap_push();
+    
     gtk_main();
 }
 
@@ -277,6 +282,11 @@
   (JNIEnv * env, jobject obj)
 {
     gtk_main_quit();
+    
+    // GTK installs its own X error handler that conflicts with AWT.
+    // During drag and drop, AWT hides errors so restore them for here.
+    // A better solution would be to save and restore the X handler.
+    gdk_error_trap_pop();
 }
 
 /*