The URL above is the print sample page from the USPS with regards to printing a click-n-ship label. It loads the url: https://sss-web.usps.com/cns/servlet/com.usps.cns.web.pdf.LabelGenerationServlet?sample=false&productCode=PRI&dummy=file.pdf Into an iframe after processing the request server-side. However, the iframe is hidden, and the link to that pdf is not displayed (which is their failover in case you can't see the iframe, strangely enough). Therefore, the hidden iframe does not print. I can't find any script that actually sends the print command to the browser, and this may be because the PDF file itself contains that code. (If the pdf is saved to disk and opened in Acrobat, it immediately pulls up the print dialog) The only workaround I have found is to do a view-source on the page, extract the above URL and paste it into your browser to view the PDF fullscreen and then print it manually. Unsure if this is a webkit bug, a pdf bug, or an issue for 3rd-party PDF plug-ins.
Change that second url to: https://sss-web.usps.com/cns/servlet/com.usps.cns.web.pdf.LabelGenerationServlet?sample=true&productCode=PRI&dummy=file.pdf (sample=true instead of sample=false)
Please try this on a WebKit nightly build and report back the results (and the build number: rNNNNN) in this bug. http://nightly.webkit.org/ Thanks! This sounds like another visibility/iframe bug, but I don't recall the bug number.
*** This bug has been marked as a duplicate of 4151 ***