[Workspaces] Workspaces Editor should remember it's window size (and position)

[detlefs]

Description of the new feature / enhancement

When opening the workspace editor, it always opens the same big window in the center of the screen. The big size is not necessary and users may have different preferences. So if user resizes the window, this should be remembered when the window is opened next time.

Scenario when this would be used?

Whenever starting or editing a workspace

Supporting information

Current behavior may be more annoying on big screens than on small screens. For me the window is always opened like 90% empty

[bergamin]

I didn't see your post at first, but I opened another issue with a suggestion on how they could do that: #34636