To reproduce,

1/ in the File -> New -> Project dialog select Seam -> Seam Web Project,
2/ switch configuration to eg. JBoss Seam Portlet Project v2.0,
3/ hit back button and
4/ try to create any new project that has not been loaded before results in an empty screen with a single disabled drop-down menu (screenshot attached) rendering the "New" dialog unusable.

Workaround:
restart the dialog or dont use the back button

This is a trivial issue however might discover similar issues in the New dialog.