I originally thought this is just gvim (see bug 15802) but I just noticed that Galeon does this as well, so I am assuming it's a problem with all gnome/gtk applications. For example go to a site that requires sign-in (like the gentoo bugzilla) and enter a random username/password in the textbox. Galeon will prompt you to save the password. Notice that the dialog has no accelerators.
*** Bug 15802 has been marked as a duplicate of this bug. ***
No longer a problem: gtk+-1.2.10-r10.ebuild fixed this.
cool, unexpected side effects ;)