How to register a window in GTK ?

[Dipak G Patil <dippatil in ibm com>]

Hi,

I am porting a application from MS Windows
to linux using GTK.

Could you please tell me how can I register
a window class in GTK, as I did not find anything for the same, like there
is API RegisterClassEx in windows?

Also, does gtk_widget_show
repaints its own window area,
as I did not find function like windows UdateWindow(). 

Thanks and regards,
Dipak G Patil.