[JS CS3/4] ScriptUI How to color a button ?

Is it a way to get a colored button in the ScriptUI DOM ?

I tried

dlg.button1.graphics.backgroundColor = dlg.button1.graphics.newBrush(dlg.button1.graphics.BrushType.SOLID_COLOR,[0.7,0.7,0.7],1);

But although the dialog is drawn, the button is not styled in best case, not visible in the worst case.

Is that possible to get a colored button ?

Hope so.

Do you have any tip ?

TIA

Loic