Maybe I am not giving up yet.
I downloaded the free version of Ample Guitar, and it does work in LMMS, probably also the strum part.
Now I need to figure out though, how this plugin works.
I did already find the strum part were you can pick also if the up or down strike is muted.
https://www.youtube.com/watch?v=_qj30Tx3V3s
I am back to LMMS, Ardour drove me almost insane.
With all kinds of respects, I want a piano roll but this might have to do with me not recording music I play, only exception some midi which LMMS can record.
Looking at reaper though, because it has swing.
For some part this is totally frustrating to me.
Yes LMMS is a bit limited but for what I want to do its not missing much.
Swing and humanization.
After an intensive search I learned that two daw do have this out of the box.
Cubase and Ableton.
Which don't have a Linux version. 