urxvt: PLEASE REPORT: pty_fill on full buffer

[corrado]

I should use urxvt for prints by the "transparent printing"
functionality, it work fine if the characters to be printed not exceed
2048, after I see the error message: urxvt: PLEASE REPORT: pty_fill on
full buffer.

The .Xdefaults config file is like this:
urxvt*print-pipe: gtklp

The file to be printed appears in this format:
ESC[5i
text text text....
text...text
ESC[4i

how I can enlarge the print buffer?

Many thanks for the answer
Corrado