After updating to GWT 2.0.1 (official) and moving our project to a arch/vbox, I had a small adventure trying to get DevMode window to come up: it just wouldn't. The window just came up blank and nothing else happened.
It turns out you are running awesome, Java may not play nice. You need this:
And remember to export GDK_NATIVE_WINDOWS=true to make all your Eclipse buttons work correctly.
Thanks to selckin on ##gwt for wmname suggestion.