This is the first step to moving redo out of the top-bar, see: T55039 - Support for floating panels in the ScrArea has been added. - A new region type RGN_TYPE_HUD is used for floating settings input. - Only one HUD should be visible at a time. - Currently HUD regions are only visible for 3D view and image space types. - There are currently some remaining glitches with hide/show that need further investigation.