Sometimes the sub menu in the alt-tab switcher (the one that lists windows for the same application) is horribly stretched vertically and does not even fit on the display. This is probably related to dual displays, I've not experienced it otherwise.

I'm not sure if this is reproducable yet but it has happened before and this is how it happened this time:
* docked the laptop, for some reason it mirrored monitors (it does not normally)
* used "Displays" system setting to not mirror and to increase the resolution on the external display
* The gnome-shell panel and alt-tab switcher are now on the smaller laptop display
* the alt-tab sub-menu is fugly (see screenshot). The mis-transform is weird: one clue as to what might be happening is that a single window "screenshot" seems to be non-stretched: a very tall and narrow one.