Applies to Photoshop CC 2015.5.1 Creative Cloud version on Windows 7 Pro .:The Quick Info (onclick window, where you can quickly see and display image size and dpi image resolution, for example) is not visible at the bottom of the status line (in the left area), depending on the image / background. The problem affects the tab as well as the floating window. See also the screenshots. The Quick Info window is only readable after the image has been moved out of the work area (screenshot 3, bottom). In previous Photoshop versions, e.g. CS5, was better off, as these info data always stood in front of a white background (not transparent). In the basic settings I have found nothing to change this.
My suggestion to the Photoshop development team: White background (and black font, no transparency at all) in this info window, so it is always good and fast to read.