#26834: [tk-3dsmaxplus] 3ds Max is crashing if we merge 2 objects

This is more than just maxscript evaled from a dialog, right?  It is if any maxscript is run while a modal dialog is being shown and that maxscript ends up prompting for something, right?  (since modal dialogs are not really modal)

Since there is no real guarantee that there is a modal dialog being shown when calling this (it should be safe to call whenever and should protect you when there is a modal).

So there should be a check in the code for the dialog variable being None, in which case it would just call the func.