up limit of share dropdown from 4 to 15, scrollbar after 4 1/2 entries, fix #135

Finally. Check it out @Raydiation @MTGap @tanghus @DeepDiver1975 

The cut at 4 1/2 is to visibly hint that there are more entries below. I upped the limit of the pulled users from 4 to 15 – maybe that can even be fully removed but I don’t know.

CHECK AND LET’S PULL THIS IN!