Using Screensaver "settings" freezes system and rundll goes out of control

reactos-bootcd-0.4.15-dev-6397-g6b7efb3-x86-gcc-lin-dbg

• Open Desk.cpl
• Select 3D Screensaver
  • Massive logspam of "(win32ss/user/ntuser/message.c:945) err: Message WM_PAINT count 0 Internal Paint Set? FALSE" as already logged : https://jira.reactos.org/browse/CORE-5601?focusedId=139925&page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel#comment-139925
• Overall CPU usage is fine following fix of CORE-8217

• Change screensaver text (in this test, to an empty string, but does not matter)
• Display not refreshed and rundll32 goes out of control

• Same bug when using "Logon" screensaver and click on "Settings" button after accepting the message box

Likely culprit : WaitForSettingsDialog in dll/cpl/desk/screensaver.c : https://git.reactos.org/?p=reactos.git;a=blob;f=dll/cpl/desk/screensaver.c#l223