Ctrl-z cuts the bottom off all my frames

[Darren-Hudson]

Bug description

(this template is intended for bug reports, erase it when requesting features/enhancements)

Steps to reproduce the bug

1. go to piskelapp.com
2. Fill a few frames with colour
3. Press Ctrl + Z, sometimes it is fine but most of the time it cuts the bottom off the frames.

Environment details

• operating system: MacOs Mojave
• browser (or offline application version): Chrome

Feel free to include a screenshot of the bug, a .piskel file of the sprite or anything else that can help us investigate.

[ddekany]

Also this happens quite often, and to make it worse, when Ctrl+z deletes the bottom of all the frames, not even Ctrl+y (redo) will bring it back.

To consistently trigger this bug, do this:

1. Go to https://www.piskelapp.com, "Create Sprite"
2. Unzip attached .piskel file: bug-925.zip, then "Import" (folder icon on the right) it, and chose "Replace". Do not chose "Combine".
3. Press Ctrl+z. Or, draw something and then press Ctrl+z. Lot of pixels will be gone from the bottom of the screen.

Tested on Windows 10, latest Chrome, also latest Firefox.

Workaround: Seems to me that this is related to importing the file with "Replace". If I use "Combine" (not ideal), then Ctrl+z works as expected.

[PoolloverNathan]

Seems to only happen after hiding frames