Hmmm. I have a subscription to both LMD VCL Complete and Finalbuilder.
Though I love Finalbuilder, the docking solution it uses is unsuitable for my own application. Finalbuilder is basically an IDE, I love it, but the actual fiddling with action properties is done with modal dialog windows son one can only fiddle with one thing simultaneously.
And re-arranging docked panels is by no means trivial. You see, once you detach a panel it has to fit into a rectangular space somewhere. You can't just place the panel anywhere you like, it's not like other panels will intelligently move out of the way if you want to drop one somewhere. When I try, I find myself dragging a panel around, hoping it will snap in somewhere suitable. So once I have a usable layout, I simply try not to break it!
MDI may not be the prettiest solution but it actually solves a ton of problems. Open a dozen views or editors at once? Check. Auto-align them all? Check. Want to maximize one of them? It takes just one click. Restore the previous situation? One click.