Can the border size be set at runtime?

[Lewis Pike]

Does urxvt provide an escape sequence to alter the internal border
size of terminal window on the fly?  I had a look through the urxvt(7)
manpage but didn't didn't find anything pertinent.

I'd like control over this visual element so that I can set the
internal border size to 0 when switching the window to fullscreen via
a perl script and wmctrl.

Might anyone know how to do this?

.lewis