collapsible sidebar instead fixed dropdown file selector

[sgohl]

I have hundrets of log files and often they have very similar names.

It is very cumbersome to find the file I am looking for by scrolling half a day through the drop down menu which only shows 9 files at a time.

What about a collapsible sidebar (which does not forget the file I clicked last) with full height and width calculated by the longest filename? As soon as a file is clicked, sidebar should collapse. Position of the sidebar should be left