In the right column of these fora is the place that shows the user's avatar and several links for the user to use to interact with other features of this form and such ("Public Profile (Edit)", "Change Avatar", "Conversations", "Your Friends", etc.)
The background of that small rectangle is initially white. If I open another window (or even just switch tabs in IE) such that that rectangle is hidden from view and then re-show that window/tab, the background will often (but not always) be dark gray.
If I then scroll the window such that the area is moved out of view and then scroll it back into view, it MAY have returned to being white. Or, sometimes only a portion will be white.
If I drag a window of another program over that area (or a portion of that area) and then move the window away, it may or may not change the background color of that rectangle to white or dark gray. (Playing with this I can get a sort of checkerboard look to the background!)
I cannot duplicate the action while writing this post, but I can do so on any page when reading another posting or viewing the forum main menu.
Not a big problem, but a simple oddity of just that rectangle on the page.
HA! It doesn't do it in THIS forum! But it still does it in other forums.