Collapse floating panes
Floating panes are nice in theory but in practice they get in the way quickly.
I work with floating toolboxes very often in apps like Adobe Illustrator, where you can collapse them a number of different ways -- into icons, into titles, into small versions of the toolbox, and so on. In Pro, the options for your floating pane are limited. You can certainly resize it into something like this manually...
Yet you have a relatively small target to grab, and it involves some dexterity to slide your mouse around to open & close it all the time. Double clicking the header is one solution, but then you've covered your main application window with a huge pane.
For workflows where you really want to see as much map or layout as possible, or want your tools closer to where you're working, some sort of collapse option would be very nice. Docked panes have this option. It would be very useful when working on a vertical monitor, where docked vertical panes eat into your real estate very quickly.