Does anyone know how to remove the resize grip widget? I'm running Lubuntu 13.04 and have created a custom Metacity theme running within a custom desktop session. All windows have a coloured rounded-edged border, which is specified in a bash script. Editing the colour value in the script changes the colour of the window borders.

My problem is that the effect is being completely ruined by the grey bar and triangle along the bottom of the windows. There is also a grey area at the top left of every window (again, where the context menu is accessed).

I'd really like to know what I need to do to turn this off.