Sorry to revive this old thread, but I have difficulty printing with GeckoFX. When I call window.print () the print dialog box is displayed, but pressing ok printing is not performed. If I try to print a second time, an error appears: "Printer Error, not available".
In Visual Studio I see the following error:
Skybound.Gecko.nsIWebBrowserPrint.print (nslPrintSettings aThePrintSettings, nsIWebProgressListener aWPListener).