Please what is this.. ??!
 

This thing appeared but i don't know why ?! (don't remind what change i had done, but was a video setting, surely)

What is this white square ? Nothing can be done with it, and i can't get it out...

LAlt + R Mouse button!

Well, thanks ! :eek: :-P
But what is this ? :confused: :grin:

I take it you didn't read the FAQ here?

It says:

"5. Q: I am seeing a gray rectangle in the upper left corner of the screen.

A: You have created a new Info window. These highly customizable windows allow you to set up your own user interface in-game. Due to the fact that the game also features clickable cockpits, our solution to having distinct clickable elements that possibly overlay each other is making the cockpit elements selectable with a regular left-click, and the interface overlay windows selectable with an alt-click.
So, simply alt-click the grey rectangle to select it, and then either move it and resize it, right-click to customize it, or right-click to close it.
This can also be done with all standard interface elements, including no-cockpit gauge overlays. Or you can right-click anywhere on your screen and add new Info windows to your interface layout."