gtk_enumerate_printers shows disconnected printers

[Marco Ricci <marcoricci2012 yahoo com>]

I wrote a simple program that calls gtk_enumerate_printers() and does nothing else. In the function that is 
called for each printer (the first argument of gtk_enumerate_printers), I call gtk_printer_get_name and print 
the name of the printer.

Everything is fine up to this point and I see two printers in the output - one is "Print to File" and the 
other is the name of the printer connected to my USB port.

I then turned off the printer that is connected to the USB port and even disconnected it physically. On 
running the program again, I still see the same two printers. 

Why is this the case? Shouldn't the printer that is no longer connected to the computer not show up anymore? 
If I am mistaken, can someone tell me how I can identify which printers are no longer active? 
gtk_printer_is_active returns TRUE even though the printer is no longer connected.

Can someone please explain how this works and how to overcome this problem?

Thanks,
~Marco