Negative Border Radii Proposal

This is a proposal for a different interpretation of negative -moz-border-radius values.

Basically, negative values would "eat in" to the box. For example, with:

   div { -moz-border-radius-topleft: -128px; border: thick solid; }

...one would get a square with a quarter of a circle with a 128px radius cut out of the top left hand corner.

This is the opposite of what occurs with positive -moz-border-radius:

If this has been implemented, then the following should be the same as the reference image:

See bugzilla bug 24039.