I don't understand the very large X in the upper right corner. Typically these appear when a window has appeared on the screen, and the X is how you dismiss it.

I don't understand the very large X in the upper right corner. Typically these appear when a window has appeared on the screen, and the X is how you dismiss it. Here, it loads with the page, so it's not clear if I would want to click it to 'dismiss' what I'm currently seeing. But since I don't know what's behind this (or how to get the current view back), I would be hesitant to click it.