Bug#550183: Breaks Default button in some eclipse dialogs (and rcp apps)

[Kyle MacLeod]

Setting the environment variable GDK_NATIVE_WINDOWS before starting 
eclipse seems to have fixed this issue for me (from 
http://bugs.debian.org/cgi-bin/bugreport.cgi?bug=548704 which references 
http://library.gnome.org/devel/gtk/2.18/gtk-migrating-ClientSideWindows.html)

Hopefully it won't cause other issues with eclipse (I've only done some 
minor testing but all seems well).

-Kyle