Hi,
I'm using KDE 4.11.3 on Fedora 19
I cannot configure a printer. I go to settings, then printers. root passwd is asked, prompted, okay. I have this window :
see http://pix.toile-libre.org/upload/original/1383944295.png

now if I want to modify a printer, I can change options, then I click "apply", root passwd is asked but I cannot have access to the field in which to type the passwd.

I can modify my printer using cups&firefox though.

let me know if I can provide any more information. thanks in advance for your help and advice.

Can you please provide a screenshot indicating why you are unable to enter your root password when modifying the printer?
Are you unable to focus the window, or does it simply not accept input?

I had the same problem, not able to focus the window where to enter the root password. I have to configure double-sided printing and resolution. I'm using a Samsung ML 2851ND, KDE 4.11.3 on openSUSE.

Please provide a screenshot of the window you are unable to focus.