In the link below there is a typo:
global proc string InitializeCommand(int $surfaceName)
argument should not be an 'int' but a 'string'
global proc string InitializeCommand(string $surfaceName)
Doc with typo:
https://knowledge.autodesk.com/support/maya-lt/learn-explore/caas/CloudHelp/cloudhelp/2018/ENU/MayaL...
Same typo here:
http://help.autodesk.com/view/MAYALT/2018/ENU/?guid=GUID-048A5F9C-FA4F-4F4C-A15A-5054F9C3FD1A
I haven't checked other places or versions but it's most likely wrong in other places.
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Side note, in the MEL documentation of artUserPaintCtx http://help.autodesk.com/view/MAYAUL/2018/ENU/?contextId=COMMANDS-INDEX the callbacks signatures (-initializeCmd, -setValueCommand etc.) are never defined and it's quite confusing / hard to find. It would be nice to improve the MEL documentation by adding signatures of every callbacks and add a link to the above tutorial (for instance in the summary section of the artUserPaintCtx MEL command). IMHO this tool is quite extensively used and could benefit from more in depth documentation.
Cheers
@tj.galda