If you see the message
tDOM wasn’t compiled for multithreading
on doing “package require tdom“, the problem is related to the TCL implementation being multi-threaded while the version of tdom library that is being loaded was built without multi-threading support. The fix is to install a version of tdom with multi-threading support. Run “teacup install tdom” to get latest from ActiveState. It seems like version 0.8.2+ of the Windows DLL of tdom is built with multithreading support. It is possible that you already have multiple versions of tdom. So try using the package command with the version option as “package require tdom 0.8.2“.