applets/taskmanager: At least show something when thumbnails are disabled
There's an option to not show window thumbnails, but when you use it, all tooltips for tasks disappear, not just window thumbnails. This isn't ideal since you lose all feedback about the hovered task. In addition, the behavior doesn't match the text of the option, since more than just tooltips disappear.
Instead, show the small title-and-subtitle style tooltips.
BUG: 492530 FIXED-IN: 6.3.0
How it looks now with thumbnails turned off on various types of Task tooltips:
I tested this with both vertical and horizontal panels and with the option on and off. There are no visual changes or regressions for the status quo.