Rect getVisible method do not account for elements with fixed position.

[nilsfr]

The getVisible method in the Rect class do not account for elements with fixed position.

Elements with fixed position can "escape" the overflow hidden attribute of a parent element.

My use case is that I am creating a plugin that can put the editor in a "full screen" mode. This makes Ckeditor cover the whole browser window. This is done using fixed position. This works fine except when Ckeditor is placed inside a parent element having overflow value other than visible.

So when Ckeditor is placed inside a modal "window" the "full screen" mode makes Ckeditor behave weirdly. I attach a picture of the effect.

Fixed elements are shown even if they are inside an "overflow-hidden" element.