Today’s example sponsored by gdm. Say that you have a certain session (gnome, kde, fluxbox, whatever) and you’re experimenting with another one which isn’t working quite smoothly yet. Then you’ll be stuck going back and forth a few times. And you’ll probably see this dialog:

The Ubuntu gdm theme is nice and clean and it’s easy to figure out how to change the session. This dialog does the job without much ado. But then you find this:

After you’ve changed the session, assumed that the change succeeded, stopped thinking about it, and moved on to start the session by logging in, you get this idiotic dialog.
This is horrifying in several ways. First of all, the gdm login screen is completely clean of any dialogs, so there is no hint given that you should expect a popup. Secondly, once you’ve set everything using the secondary controls at the bottom of the screen, you just want to login and be on your way. When I’m in that mode, I’ve basically learnt to hit Enter as many times as it takes to get me through, so I’m very likely to accidentally accept the dialog since I don’t know it’s coming.
And finally, the question of whether to make the session the default one is completely cut out from the menu for changing the session, which shows a complete lack of consistency. Here I’m done doing something and later on I have to answer unexpected question about something I already finished.
Not to mention that the “unsafe” choice is selected by default, I might accidentally change my default session just by clicking Enter twice after putting in my password.
Worst of all, even when I know that the popup is coming, I absolutely do not want to have to answer it again and again just because someone couldn’t figure out a better place to put that option. Make it a checkbox on the previous dialog, that’s what everyone else does, why must you be so special?
I’ll be nice and I’ll just call this sloppiness.
EDIT: Bug filed.
UPDATE: Bug fixed in gdm 2.21.