I have a Chrome browser window open and it in turn has a window open to allow me to upload a file. I clicked open and it sort of went away and sort of didn't. Please try watching the brief clip below and then put that situation into words because it defies me. Is the file explorer window there or not? Either way, I can't access that Chrome window because it thinks there's something open on top of it.

You can see the file explorer window is open in the preview you get from a mouse over on the taskbar but if you click the taskbar icon to select the relevant Chrome window then it isn't there but it is but it isn't but it is but it isn't....