Ted Drake zu der Frage: Should a web site open pdf files in a new window?
Vorweg sein Ergebnis:
Web site visitors expect to find information in an efficient, user-friendly manner. It is up to the web designer to create this experience. While opening new windows may be considered a faux pas, the average user will actually appreciate its convenience. JavaScript offers the most convenient method of giving a visual reference and functionality. Placing a helpful title attribute within the link further informs the visitor about the link’s behavior.
Zunächst sollten Links auf pdfs als solche gekennzeichnet werden - z.B. mittels css:
.pdfFile {background: URL(pdflogo.gif) no-repeat 0 0; padding-left:25px;}
Popups oder nicht beantwortet WAI recht eindeutig:
WAI Checkpoint 10.1
Until user agents allow users to turn off spawned windows, do not cause POP-ups or other windows to appear and do not change the current window without informing the user.
http://www.w3.org/WAI/wcag-curric/sam77-0.htm
Um validen Code zu schreiben, der pdfs in einem neuen Fester öffnet verweist der Artikel auf ein JavaScript von TJK Design:
Opening Popup Windows with no extra markup.