just some minor things which I think might improve the GUI usability:
I often sit at my notebook which has a 16:9 screen. In browse mode u have use the menu button to add a directory (or song) to the playlist. IMO it would be much better to move the menu button to the left side, right before the dirctory name as not only you have to move over to the other side of the screen for any action (which is quite a long way to move if u are on a bigger landscape format screen) but also raises the probability for clicking the wrong line.
Related to that would be that I would like to highlight the line you are hoovering over in browse mode.
Next wish would be the possibility to change fontsize and line height (like + and -) in browse mode so I could view more lines at one time when on a big monitor.
Last thing that comes to my mind atm would be realted to the search function in browse mode. Its results should include directory names in listings as well, instead of resulting only songs - this would allow you to play the whole album you searched for with just one click.
Thanks for listening to my suggestions