I use a custom keyboard layout, which is set up by X11 as:

Option      "XkbLayout" "zap(us_ro),zap(ru)"

Now with latest gnome when entering a password on GDM screen it will allow me to choose either one (although only the second "works", utf-8 characters are not allowed in passwords?). But in ~/.dmrc I'm left with:

Layout=zap

This is wrong, because the variant is missing, and the "zap" layout with no variant is empty. This, in turn, has the effect of adding the "zap" layout unconditionally to my keyboard layout set up (e.g. in System->Parameters->Keyboard->Layouts I will see *three* layouts: "zap(us_ro)", "zap(ru)" and "zap", and ISO_Next_Group will cycle between three groups rather than two, one of which is unusable.

This problem will arise with any layouts using variants - e.g. for example users which will want the "ru(typewriter)" layout will get in the end two layouts - ru and ru(typewriter) due to the annoying habbit of the gnome-settings-daemon's keyboard plugin to append GDM's layout to user settings at every login.