Uhm, in the long run I believe it will be better to move to
Tcl_CreateObjCommand since it is said that commands created by it are
significantly faster than the ones created by Tcl_CreateCommand (more
information about this can be found at tcl documentation).

I'm only writing this because, as other places that deal with tcl
objects, more care must be taken. For instance, I have applied the
issue1028.diff on the tk_and_idle_maintenance branch and found two
problems that are now patched by adjusts1.diff. It is very likely that
there are other bugs around, I'll be trying some tkinter applications to
try to find some of them but help is very much needed. Note that there
are some tkinter tests on this tk_and_idle_maintenance and they all
pass, but they do not fully cover tkinter at this moment so improving
them would be good too.