gEDA-user: Can't truncate plane layers on backside?!?!?

[sdb@xxxxxxxxxx (Stuart Brorson)]

Hi PCB hackers,

I have created a simple PCB with a back-side GND plane.  I define the
plane  using a polygon drawn on the solder side.  The polygon
terminates about 100 mil before the edge of the board.  That is, the
GND plane is 100 mil smaller than the PCB outline along all four edges
of the board.

When I export the Gerber file & view it, the GND plane extends to
infinity.  However, I though I drew it to be smaller than the PCB
outline.  Um, what am I doing wrong?  Or have I found a bug?

If requested, I can post a .pcb file & some Gerber snapshots.  But
maybe this is just newbie confusion. . . . .

Stuart