TQt only needs to be rebuilt if Qt is changed/upgraded. It is nothing more than a thin wrapper on top of Qt to provide the "old style" features that were removed from Qt4, as well as a good place to put Trinity-specific widgets so that they are available to all Trinity applications.
Okay. But you stated previously that qt3 should be rebuilt with each new distro release, which then implies rebuilding tqtinterface too.
I did? I don't remember now...heh.
Bottom line is that it would be a good idea to rebuild it on each new major release of your distribution. Anything in between those major releases shouldn't require a rebuild, as the Qt ABI for minor/point releases is quite stable.
Tim