Thank you for quick diagnose, Florian!
I use several programs for *.m3u files pinned manually to this type of files by the edit of the registry under right-click, but default is Mp3tag exactly.
So, if I can not change the connection to that type, I have to understand, it is the "feature"?
It is a little confused, because if I forget about it and I forget it anytime, Mp3tag erase whole part of my job without any communicate, so maybe this will be the good idea to change behaviour of the app or add any communicate window to ask, if I can do that, as you added it to not saved changes in the panel by changing focus in the app?
P.S. I I have asked you several time in the past about changing behaviour of Dialog Windows of the app in Dual View mode of Win10, but you did not answer.
What I need is to change their position from fixed to moveable as you did for some of Dialog Windows in the past (e.g. Dialog Window for "Action" and "Quick Action" or Replace are unfixed now).
"Reading Directory" Dialog Window or "Playlist Save" Window e.g. are still fixed to the center of the app's window size in horizontal and vertical.
Check please, that the new behaviour of Window 10 (leaving margins of pixels around edges of the Desktop) collides with that behaviour of those fixed Dialog Windows of Mp3tag, because when application is used as long as two or more monitors, if Win10 moves app's main window to fix Desktop margin size, what happens anytime automatically during start of the app, those Dialog Windows several times move to the second monitor not primary as expected, so in any error, the communicate is also not in front of my eyes, but on the second monitor, so I am waiting for app, which is waiting for me because of error waiting to read and accept or reject.
P.S. 2 Next error in the app during use 2 monitors is that one:
if I change Desktop size from Dual View to right monitor only (Win+P) and left monitor is off, the app is still fixed to that one the most left (for me secondary), which is now switched off. In that case only right edge of the app, no more than width of the button Close, is visible on the right monitor, so I can not move the app to working monitor manually (I have no visible place of the bar of the main window of the app than Close button to click and move and Close button is not available to dragging). I know 2 life hacks, which are: to chose Cascade Window from Taskbar or switched left monitor on for a while to drag app's main window to primary right monitor, but it is not solution, right?
So, may I ask you to change the behaviour of the app in the system with Dual View for both errors about?