Hicolor icon theme

[John Emmas <johne53 tiscali co uk>]

I'm not sure if this is the right place for my question but if not, 
maybe someone will point me in the right direction....

About 2 years ago I built the Ardour DAW which was then at version 2.  I 
built it for Windows, using MSVC.  Naturally there were a few problems 
but eventually it all worked.  I'm now trying to build Ardour3.  Ardour3 
still uses GTK2 in case that's significant.  GTK2 and all the other 
libraries are also built (by me) using MSVC

The build itself seems to have gone okay but when I try to run it, GTK 
complains (and subsequently crashes) because it can't find the "hicolor" 
theme and icons.  In particular, it crashes when trying to load 
something called "edit-find" (a cursor maybe?)  Each time it crashes, I 
see some debugging output which directs me to this web page:-

http://icon-theme.freedesktop.org/releases/

Various themes are listed there but I've no idea how to install them (or 
even where to install them!)

How do I find out more about these themes and what I need to do with 
them?  Thanks.

John