I am clicking on the Atlas button of a sprite and it only shows 3 of the 5 atlases I have in my project. When I press the "Show All" button on the chose an atlas window a searching box and progress bar pops up, the progress bar completes but the searching box doesn't then close, and now all the options in unity for saving and quitting are greyed out. So freezing up the editor. I then have to force quit Unity.
Platform Unity 5.3 on OS X with latest NGUI.
Currently no way to select an atlas that isn't in the list when it's first presented.