Why display the entire window contents when moving it?

[Tshepang Lekhonkhobe <tshepang@gmail.com>]

Hello,

When dragging a window around, why isn't only the border displayed
during movement, instead of all the details. The current behaviour
punishes CPU power and therefore some ugly, trailing stuff (try it).

I used to see this desired behaviour in one of Microsoft's OSes (it
was a thin greyish line) and thought it was excellent, considering
nobody reads anything on the window when it's being moved. The window
contents remain behind until the mouse button is released at which
time the entire thing will shown on the new location.

Is this a window manager kind of thing (I use GNOME).

...malebo