That probably means the file isn’t marked as an executable, so the program used to handle the file type is opened. I know you’ve now solved this by installing from OBS, but for future reference:
In whatever file manager you use, you should make sure the file is marked executable. For example:
Once you do that, a double-click will run the application.
Galaxy Quest 
Such a great movie
Just noticed your reply…
It looks like you’ve built DT so are sorted. However, appimages are useful and worth bearing in mind, they don’t need building for a start. To use, set the downloaded .Appimage file to executable as above, and put it in some folder, I’m using Desktop. Then in Terminal type
./Desktop/X.AppImage
where X is the name of the appimage. DT should launch.
You can keep a selection of appimages to play with if you want, you just choose which you want when starting in Terminal. This is subject to the usual position that you can’t go backwards across a major release (unless you zap the database and associated files).
Thanks a lot. That’s a handy explanation. Bookmarking it!
If you don’t need the terminal (e.g. for debug logs), you can simply double-click the AppImage. Any required parameters (config directory etc.) can be set if you create a launcher icon - check the docs of your desktop environment.
Thanks kofa
