I'm running Ubuntu 16.04 and have tried both the 17.12 and 18.08 app images. They run and work for the most part, but the keyboard navigation in the timeline does not work. Has anyone else seen this problem?
I have used the 17.04 version provided by the Ubuntu repositories and the cursor keys work fine.
I checked the Configure Shortcuts window. Forward 1 Frame is assigned to Right and Rewind 1 Frame is assigned to Left, as expected.
I tried deleting all kdenlive directories under my home directory, but that had no effect.
I also noticed that dragging the playhead does not work either, maybe that's related?
Any suggestions?

Thanks,
Chris

Do you have changed the Keyboard type/language in the Ubuntu settings? Does the arrow key work in other software? Try the newest repository. If it’s working than you have probably special settings setup in Ubuntu.