[Bug 56768] uxtheme crash when using themed CheckBoxes

[WineHQ Bugzilla]

http://bugs.winehq.org/show_bug.cgi?id=56768

--- Comment #3 from KRosUser  ---
See
https://learn.microsoft.com/en-us/windows/win32/api/uxtheme/nf-uxtheme-getth...

[in] prc
Type: LPCRECT
Pointer to a RECT structure that contains the rectangle used for the part
drawing destination. This parameter may be set to NULL.

Faulty code is here
https://github.com/wine-mirror/wine/blob/master/dlls/uxtheme/draw.c#L232 where
pRect is used with

POINT size = {pRect->right-pRect->left, pRect->bottom-pRect->top};

without checking pRect as non-NULL

(see the patch in attachment)