Something weird is going on with multi-track mode, remove track, and undo

[TRA]

Steps to reproduce:

1. Launch Shotcut.
2. Open a video or image file.
3. Move the entire thing or a portion of it to the Timeline.
4. Choose Add Video Track from the Timeline toolbar menu to add another track.
5. Open another video or image file.
6. Move the entire thing or a portion of it to V2.
7. Move the clip on V1 to V2
8. Click on the V2 track label.
9. Choose Remove Track from the toolbar menu to remove the V2 track.
10. Press Ctrl+z or choose Undo from the menu to undo.
11. Keep undoing.
12. A crash occurs or duplicate clips appear.

There were some additional weirdness such as being unable to move clips, clips becoming too long, and transitions appearing, but I haven’t been able to reproduce them. This crash and duplicate clips issues are reproducible almost all the time.

This happens in 18.08.14 and 18.03.06. I’m presuming that all the versions between have this problem.

At 7),
if I move the clip on V1 in front of the clip on V2, a crash tended to occur.
if I move the clip on V1 after the clip on V2, duplicate clips tended to appear.

At 5), you don’t have to use another file. A clip from the same file produce the same outcome.

At 4), you can also use Insert Track to reproduce this problem.

Audio tracks also exhibit this problem. To reproduce, use audio files at 2) and 5). Also use Add Audio Track twice to create A1 and A2.

a) Only tested on Windows 7 64 bit.

It might be related to these threads:

Shotcut crashes when I drag a clip, create a transition, undo it, and move the clip in certain way in the single- and multi-track modes

Steps to reproduce: Launch Shotcut. Open a video or image. Create two clips from the file. Let’s call them A and B. Place them in the Timeline next to each other. Preferably, leave some black space before A. Drag, not trim, A toward B, overlap a portion of B, and drop A to create a transition. Click the Undo button on the toolbar, press Ctrl+Z, or select Undo from the menu to undo 5). Move B in front of A. If you didn’t leave a blank space in 3), you can move A and B around before doing this. S…

or

Cutting or ripple-deleting a clip from the Timeline leaves something that acts like an edge of a clip in the multi-track mode

I was experiencing crashes while cutting and pasting clips in the multiple-track mode, but I haven’t reproduced it consistently. This problem looks benign and non-critical, but can be related. Lifting a clip doesn’t cause this problem. The empty track leaves something that acts like an edge of a clip at 00:00:00:01, which looks to me like a normal and intended outcome. Steps to reproduce: Launch Shotcut. Open a video or image. Create two clips from the video or image. Let’s call them A and B…

because both of them involve multi-track mode, and be already fixed in 18.09.** if that’s the case with the first thread.

[shotcut]

This has been fixed for the next release v18.09