Comment 3 for bug 850885

Essentially, the problem is that during login the screen resolution is resized but the screen isn't cleared; gnome-settings-daemon (or *possibly the GPU) just fills the undefined space with snippets from the framebuffer.

We could just insert a blank before beginning the login, and then unblank after, however this would cause an undesirable flicker for normal cases, where the screen resolution does not need to be changed.

Perhaps a better approach would be to alter gnome-settings-daemon such that when it does a mode change during login, to either blank or scale the existing framebuffer, rather than the ugly tiling.