This is not just about looking native. This is about integrating Abrowser
with KDE. If you use the patched version of Abrowser, it will use KDE
open/save dialogs and the KDE file associations. You may have noticed that
files open by default with the default application configured in GNOME. That
won't happen if you use the patched version.
For looking native, I recommend a patched version of gtk2-engines-oxygen. [0]
I submitted a package helper on trisquel-dev, but no one responded, so I will
upload it to the PPA later today.
[0] http://trisquel.info/en/issues/10944