Transparent windows: how to get rid of it?

[Colin Law]

On 3 December 2011 09:59, Freddy Van Ingelgom <freddyek at gmail.com> wrote:
> I think that my question is confusing the way I posed here. In fact I should
> not speak about a window, but I do not know how to name it: sometimes it
> appears on the screen as a sort of indication were to put a existing window,
> a sort of placeholder or how should I name it? It is a sort of transparent
> rectangular that appears on top of my desktop and it does not affect the way
> I worked, it is there, I can see and continue my current work, and the only
> way to get rid of it is to resize a window, place it on this transparent and
> then the window takes the size of that transparent which disappear and after
> that I can return to the size that i like for my current work (Firefox for
> example, or whatever).

Very strange.  Are you able to get a screen capture with it visible?

Colin