this'll occur in an empty file, just add sprite and second animation (can be blank)
when you have multiple animations, the image editor reverts back to the first animation after the following:
Steps to reproduce:
1. Make any change to an animations image (or add a frame, but not duplicate or delete frame)
2. select the floor fill tool (you dont have to make another change)
3. select any other animation
or
1. rotate, resize or crop the first animation
2. select any other animation
i didn't test all possibilities, so there's probably other combinations, but these two seem to happen every time.
it also happens when you create a new animation.
Observed result:
reverts back to the first animation
Expected result:
stay on the selected animation
Operating system & service pack:
win7
Construct 2 version:
r150