Timeline frame disappear

[MrStevns]

Issue Summary

bug3.mp4

In the video above you can see that after the timeline selection is deselected, the current frame disappear from the timeline.
Although the frame will re-appear if you click on the frame.

Actual Results

The last frame disappear when the timeline selection is undone

Expected Results

The last frame not disappearing

Steps to reproduce

1. Draw a stroke on keyframe 1
2. Create a new keyframe on pos 2
3. Select both keyframes on the timeline
4. Draw a stroke on pos 2
5. undo the action

System Information

• Pencil2D Version: 0.7.0