Better floating window behavior

[timothyqiu]

I'm not sure how to describe the problem accurately. Currently, when a dock is made floating, it becomes an independent window.

Let's compare with GIMP in multi-window mode.

• On the taskbar
  • Godot: Floating windows are their own entry
  • GIMP: Floating windows are not shown
• When covered by other windows
  • Godot: Windows have to be brought to top one by one
  • GIMP: Showing the main editor also brings all floating windows to top
• Z Order
  • Godot: Focusing the main editor makes it cover the floating windows
  • GIMP: The main editor is always behind floating windows