Disable Mutter's window edge lines that appear when minimizing

[zp]

I'm talking about the effect that happens when you minimized a window in metacity. It would draw black lines around the window and them resize them in steps while the window was minimizing. Here is a screenshot for better clarification: http://img212.imageshack.us/img212/1477/screenshotresizedvx5.jpg

It looks really ugly and there is no need for that. I also noticed that it likes to draw those lines around Docky's urgent hint glow.