widget capability question: spin box / combo box hybrid, does it exist?

[Neil Zanella <nzanella gmail com>]

Consider a multiprotocol application. In a window such application
displays one combo
boxe and one spin box. The combo box allows the user to choose the
protocol name.
The spin box allows the user to choose the port number. Each protocol
has a default
connection port.

What I would like to know is: does GTK have a spin box where you can
bind text to
numbers. For instance, if the user chooses telnet, I want the string
default appear
instead of the value 88 in the spin box. Qt's spin box does this. I
wonder whether
the same is true of the GTK widget for spinboxes.

It is useful: I don't want my users to have to remember port names,
especially since
for some protocols these are not even sure not to change in the
future. There are
other solutions, but does the GTK combo box have this feature, which IMHO
seems like a fairly good solution (a hybrid between a combo box and a spin box).

Thanks,

Neil