[directfb-users] Why Windows manager can move my Surface?

["Jack Liu (Shanghai)" <JackLiu@viatech.com.cn>]

Dear all.
	I use DirectFB as follows:

Create a  primary layer.
Create a window on the primary layer.
Create a surface withe the same size of the primary layer.

Then I can Move or Resize the window using <Meta> key as discribed in
Readme.
But I can also  Move the backgroud(the primary surface), and from now on,
the window can not be moved or resized any more.
What's the problem? and how can I prevent the windows manager from  moving
the background((the primary surface)?

Thanks and Best Regards! 
Jack