What happens if you unlock it and forget to lock it? Or would this be locked all the time to totally prevent drawing on any frame other than 0?
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We had a similar discussion on the Animation Master forum in regards to the "Big A" button. There is this "Big A" button at the top of the tool bar. If you click this button "off" then you don't add keys in the timeline. So if you translate or rotate an already animated object on frame 300 it moves the object based on the position at frame 0. You follow? You can globally move all the keys (AS needs that).
The problem arose because many people would forget to turn this button back on and spend a lot of time keying bone rotations for a pose or move an object and not realize they are not adding key frames or had moved a carefully positioned object all over the place.
Much discussion ensued regarding solutions. Make the button HUGE and have it VIBRATE annoyingly when it was off. Or have a huge warning pop up telling you that the "BIG A" button is UNCHECKED.
All of this tongue in cheek to some extent... because no matter how in your face or annoying a warning might be when your are in the zone everyone will at some point forget to check the "Big A" button.
I of course suggested a taser like wire connected to your chair that would be activated when keying with the "Big A" button unchecked.
-vern