background image splatchscreen center

[frdt]

Hi
I try, as see in the wiki about customizing the skin, the function @image to setup a background image in the logon screen
I juste added the line in skin.properties
ChromeBg = @image(SkinImgDir, ChromeBg.jpg, 100%, 100%, )@

background is well displayd but in repeat mode
I just want to center the image on the display
I had try the "center" parameter in place of "repeat" .. no result

any ideas ?

thx