Bug 478444

SUMMARY
When editing one keyframe with the transform tool, then switching to edit another existing one, the keyframe data of the latter is replaced by the former, while the data of the former is replaced by the keyframe which precedes it.


STEPS TO REPRODUCE
1. Create a non-empty paint layer, add a transform mask to it and select the mask.
2. In the animation curves docker add a new frame at some t = A.
3. Add another frame at t = B, B  > A.
4. Using the transform tool, make a change at B, for example a translation. Press Enter.
5. Add another frame at t = C, C > B.
6. Using the transform tool, make a change at C. Press Enter.
7. Switch to A.
8. Select the transform tool. Click on the canvas.

OBSERVED RESULT
Keyframe data at A is replaced by the data at C. The data at C is replaced by the data at B.

EXPECTED RESULT
The data at A and C stays intact when the user initiates the transformation.

SOFTWARE/OS VERSIONS
Linux: Ubuntu 22.04
Qt Version: 5.15.7
Appimage

ADDITIONAL INFORMATION
Appeared in 5.2.0, regression compared to 5.1.5
In my opinion this is a severe bug because it makes tween animation borderline impossible (the best workaround I could find is to force the transform mask to apply to its current frame by making a change to the document (such as toggling the visibility of another layer) between editing each two existing frames