Taxon names sometimes don't appear properly until the window is resized

[gaurav]

Could be an issue with the GUI thread or something. It would be good if we could find a file that consistently triggers this bug.

[djlohman]

Pretty much all files have this problem on my machine. It happens when you scroll. Here is a video in which I scroll through the window, then encounter the problem (notice the duplicate taxon names), then I resize the window fix it: https://www.dropbox.com/s/sutnx8l4kvuz0aw/shared_screen_with_speaker_view.mp4?dl=0