AUI panels dragging problems

Description

2021-06-06-22-48-05

Are they even supposed to be draggable?

1. Dragging the Selection Filter to other spots leaves surface that is never repainted
2. After dragging the Appearance Manager there seems to be no way to get it back behind the toolbar
3. It probably shouldn't be possible to move them into the status bar or the top toolbar

KiCad Version

Application: KiCad PCB Editor (64-bit)

Version: (5.99.0-10847-g28909c1a72), release build

Libraries:
	wxWidgets 3.1.5

Platform: Windows 10 (build 19042), 64-bit edition, 64 bit, Little endian, wxMSW

	wxWidgets: 3.1.5 (wchar_t,STL containers)
	Boost: 1.75.0
	OCC: 7.5.0
	Curl: 7.74.0-DEV
	ngspice: 34
	Compiler: Visual C++ 1928 without C++ ABI

Build settings:
	KICAD_USE_OCC=ON
	KICAD_SPICE=ON