## Purpose
[SYSDM]
- When closing System Properties page, log show
(win32ss/user/ntuser/windc.c:749) err: [00060138] GetDC() without ReleaseDC()!
because GetDC() is called (multiple times) without properly calling ReleaseDC() as required in order to release a device context.
- This module also lacks some error management in case null DC are provided (on error).
- LiveCD Userinit, based on SYSDM is affected too.
[DESK]
- Fix missing ReleaseDC related to the spectrum (color depth)
## Proposed changes
- ReleaseDC() added.
- Error management in case of null DC.
- Overall alignement of LiveCD Userinit and SYSDM.
