I forget what all but one problem is when you maximize a window by double clicking the title bar and then do it again to resize it back to a window the title bar becomes disabled, that is, you can't even drag the windows with it. We should start a thread on it I guess but I had given up.
I do not confirm that problem here; it works fine on my system when I do that.
As for fusion-icon, I did dig into it a bit. That program is a python program. Now, I don't speak python, but with the help of the search engines, I figured out how to use the python debugger, and traced the problem into how python handles threads (or subprocesses as they are called, apparently, in python). I traced the problem out of fusion-icon and into another library function.
Again, I don't speak python, but I tentatively conclude the issue has to do with the python installation in mga4. At this point, that is all I think I know about it and I may look into it more when I have time.