This is why I can't make it work - it just doesn't play, making IsPlayingMusic returning true when it's not playing music doesn't make any sense. But I can't make no sound other way with this function, so I need to make it another way.
If there is a paremeter in scene file, it play music from scene parameter. Otherwise it just "load" file with blank name (which doesn't exist), what display warning message in log. And this is why IsPlayingMusic function return false at this moment, because there is no music.
As far as I remember correctly, there was a music pause done by @krzys_h or someone else that could pause the music while SatCom & Program editor is opened or pause menu appear (and somehow it doesn't work in current builds...). This pause had a cool feature - music muted mildly, just like in for example AIMP music player. I guess this feature should be somehow resurected in some ways.
Well, I can't post nothing new, because it still doesn't work. Now I'm trying with adding MusicPause, It seems like PlayPauseMusic won't work like I thought.