JavaScript - Pos Receipt Printer

In a web based (POS) application, when user clicks on the Print This Page button, the receipt will be printed out. In javascript, I use: window.open.

The problem is that it always triggers the Print Dialog Window asking to select a printer.

My question, how can I suppress this dialog window and dierctly send the receipt to the printer?


(There are a lot suggestions on line. I tried quite a few and none worked. I am testing on IE7 and FF3).


Thanks to help.

Scott