Yessss... sure it has been asked before elsewhere. Also, I'm aware that trend is to keep everything docked and fixed (at it has been to have Windws XD menu sticked to the left for years).
But if any design tool out there still give us the possibility to undock whatever panel/palette/tool we want, is for a good reason: efficiency and speed. For example some of my most annoying, cognitive exhaustion and time wasting XD procedures are related with it.
Constantly jump from Libreries Panel to Layers back and forth. Complex layouts uses hundreds of intrincate components full of elements with their own states and inner components.Simply I want to see all them seide by side, even grouped by category, not random as it is now.