I did a clean install of Delphi 12 and found that I can not resize the debug windows (breakpoints, watches, local variables, call stack)
I have these stacked vertically in a window.
In Delphi 11, I could resize them easily but in Delphi 12 the title bars and resizer bar are not visible so I can not resize them. I also can not remove them from the stack
Docking kinda sorta works if you dock the debug/design panels to the main IDE form. That looks really ugly on a dual 4K monitor.
In RS 11 I created a floating form on the right hand monitor and placed all the docking panels on that one. That maximized the Editor/visual designer and left room on the right monitor for email and other stuff. That no longer works in RS 12.