I'm not sure if this is possible or not to implement.
i found this thread discussing about zim desktop wiki - http://www.portablefreeware.com/forums/ ... hp?p=65352
and found this quote by lautrepay
so i tried it by downloading a GTK2.x theme hereDownload a GTK 2.x theme and overwrite the \Bin\zim\share\themes\MS-Windows\gtk-2.0\gtkrc file if you want something like this:
http://gnome-look.org/?xcontentmode=100
and it worked!
i found GTK+ website here http://www.gtk.org but the language binding doesn't include visual basic so it might not work?

http://www.gtk.org/language-bindings.php
but then i found GTK#
http://zetcode.com/gui/vbgtk/
will this work?GTK# is a library that provides binding of the GTK+ to the Mono .NET languages like C# or Visual Basic
ciao!