If I perform and undo a change to an event, I can still press OK

I see that, in the latest revision, the OK button is always enabled. The HIG do not state whether this is this desirable. Supposing that it is, the bug could be considered invalid. I'm inclined to say that feedback from the design guys is needed here.

I'm inclined to say that feedback from the design guys is needed here.

Okay so if I'm reading correctly, we're talking about changing an existing event.

If the dialog has all the information it needs to store an event (time and title) the button should remain sensitive.

However, if for some reason Maya no longer has the necessary information (like if the title is removed), it should probably either:

a. Use the last known title

or b. Make the button insensitive

I think what the report is saying is that if you edit an existing event, and basically undo all the changes you make, you shouldn't be able to press ok. This makes it more consistent with the behaviour when you first opened the event, nothing has been edited yet, so the ok button is inactive.