Hi Norman,
In the specific context of attributes to the mask to which I am referring, I don’t see any that I might not want to apply a bulk change.

These parameters also have nothing to do with the location of the mask (which I don’t want to change since I have spent hours carefully adjusting it in the multiple keyframes).
There are many ways for programmers to handle these types of scenarios.
Maybe the fields which have differing values get highlighted when you select the multiple keyframes.
Or for instance, if you have multiple keyframes selected and go to apply a parameter change, the user could be notified that it will affect all of the selected keyframes, with a big OK or Cancel option.
How about a ‘tool tip’ or maybe even (maybe as a last resort), an instruction in the Help file?
Sorry, but I don’t get how adding this feature is somehow an additional support burden. If your logic was applied, I doubt there would ever be many new features rolled out because, well, they would be too difficult to support.
And besides there’s always “Ctrl+Z”
Regards,
–Doug