http://elitistjerks.com/blogs/zork/4...tbackdrop.html
The trick is the alpha layer of the border texture.
Important. The border texture must be 8-times wider than high.
Example:
16px height = 128px width
32px height = 256px width
etc.
Max-texture size sind 2048px.
So max-size is
256 x 2048px
When you call the backdrop function play a bit with the inset and the edgesize values but keep your tilesize at the size of your texture height.
Each border texure must consist 8 parts, those will be enough to create any edge- or side-texture needed.