SUMMARY If I try to drag an effect to a video or audio track header, I get a cursor indicating that the effect cannot be dropped. The only way to add an effect to a n entire track is by selecting the track and going to Timeline -> Add Effect. SOFTWARE/OS VERSIONS Kdenlive: 18.12.3 MLT: 6.10.0 OS: KDE neon 5.15 KDE Plasma Version: 5.15.2 KDE Frameworks Version: 5.55.0 Qt Version: 5.12.0
tested with the 18.12.1b AppImage. It works. I can even drag and drop “rotoscoping” on an audio track header (which makes no sense). Please try with the AppImage it could be that your installation is not complete.
The bug doesn't happen for me either with the AppImage. However, the most recent AppImage version (18.12.1b) is older than the version I reported the bug with (18.12.3). I just tested in a KDE neon VirtualBox installation, and can reproduce the bug there with both 18.12.2 and 18.12.3 using the Kdenlive packages from the neon repository, so I would be surprised if it were an issue unique to my specific installation.
The stable version works with Qt 5.11.2. You work with Qt 5.12. There seems to be several regressions in drag&drop that could be related to Qt 5.12.
Can you please test whether this is still relavant with a current version (at the moment 20.12.2)?
I cannot reproduce this bug in recent versions of Kdenlive (currently 20.12.2). It looks like it has indeed been fixed.