Issue with clicking in a dropdown when there is overflow

[ipeychev]

There is an issue with dropdown scrollbar. If the developer sets overflow property of listbox, only visible list item are clickable whereas when list is scrolled and a list item is clicked the dropdown scrolls to top and nothing is selected.

Issue created based on this question: http://alloyeditor.com/guides/how_to_use_ckeditor_plugins/#comment-2598383603

[jbalsas]

Hey Iliyan, I think this is the same as #239 that for some reason got closed.

I'll take a look.