Bug 410265

SUMMARY
There are few bugs in association apps with file types. This bugs is present in every KDE I used from 3.0 to current stable release in Neon!!!

The bugs are:
1. When I install View Your Mind (or Umberello) it does not associate it self with *.vym files.

2. When you right click in Krusader and chose "open with" and then chose app and click "remember". It do something, then it open file in decent program, but don't remember file association in KDE (when I close program and try open the same file again).

3. When I enter "System Settings" (form KDE), and go to the "Programs" and add new file type (e.g. Application/*.vym) and chose application for this file (eg. View Your Mind), and click save. It do something, but KDE does not remember this file association. Instead when I click (in Krusader) on the file it open applications tree and (stupidly) ask for app selection, and suprisingly when I chose my app and click "Remember" it correctly remember associated app to file (it open correctly file this time and every next).

This is strange as hell why such basic feature is so poorly supported in KDE?!? On Windows - which is lame due to lack file recognition by content - this feature always works as expected and newer fail!!!

STEPS TO REPRODUCE
As above.

OBSERVED RESULT
Failed to open file with associated app.

EXPECTED RESULT
1. Open file with associated app: After app installation (eg. VYM or Umbrello). Run chosen app after click on file matched pattern extension.

2. Easy associate app with file type: Right click on file *.vym, chose "Open with", chose app from app tree (eg. "View Your Mind"), click "Save". Run chosen app after click on file matched pattern extension.

3. Advanced associate app with file type: In "System Settings", click "Programs" or "Applications" (depend on translation), click "File associations", click file group (on tree), click "Add", type extension, chose app from apps tree, click save. Run chosen app after click on file matched pattern extension.

SOFTWARE/OS VERSIONS
Linux/KDE Plasma: 5.16.3
(available in About System)
KDE Plasma Version: 5.16.3
KDE Frameworks Version: ?
Qt Version: ?

ADDITIONAL INFORMATION
I observe this problem in every KDE I used. I don't know why? Krusader do something wrong? If so: Why in System Settings, when I type file extension and chose app, and click save, then it can't open attached app to the file extension.