This problem, though a little different than as shown by acmemike, repros for me.
Repro:
clean config
open 1 file with a long path.
Split window as shown.
Make slick narrow enough that the list needs an h-scroller.
acmemikes example above doesn't seem to include a scrollbar.
Slick appears to make this dropdown taller when it thinks there will be an h-scroller, but it doesn't make it tall enough - the scroll bar height seems to be more than expected.
Mike, what does it look like when you have about 5 buffers open?
Is it still too small?