Purpose: accumulate commonly encountered problems, and their solutions, for people attempting to build Tcl extensions.
Seen many times on comp.lang.tcl:
checking for Tcl configuration... configure: warning: Can't find Tcl configuration definitions
/path/to/iwidgets/configure \ --with-tcl=.../tcl84 \ --with-tk=.../tk84 \ --with-itcl=.../itcl
where those are the build and/or *Config.sh containing dirs. See the configure --help for more info.