Since the buggy update last fall (2015.2?), my LR screen shows a white rectangle to the left side of the module names. It's as if a section of the screen is missing. It goes away during the process of importing files, and is also a fixed size (i.e., if I resize the LR window the rectangle doesn't change size). It doesn't affect any operations in LR, so I've been slow to ask for help, but the latest revs (I just loaded 2015.4) haven't fixed it. I've attached two images - one showing the white rectangle and one showing it absent during the import process. I'm running a mid-2014 Macbook Retina Pro with El Capitan.