#13 SpecTcl-1.22: SpecTcl start-up error: invalid command name "._check_"

[undisclosed]

Attempting to run SpecTcl-1.22 on a BSD or linux platform returns the following:

SpecTcl start-up error: invalid command name "._check_"
invalid command name "._check_"
    while executing
"._check_"
    invoked from within
"configure_widget_data Widget_data ._check_ widget_progress"
    (procedure "FindWidgets" line 6)
    invoked from within
"FindWidgets"
    (file "/tmp/SpecTcl/SpecTcl/maingui.tk" line 209)
    invoked from within
"source /tmp/SpecTcl/SpecTcl/maingui.tk"
    ("uplevel" body line 1)
    invoked from within
"uplevel #0 source [list [file join $Base_dir $name]]"
    (procedure "Source" line 7)
    invoked from within
"Source maingui.tk"
    (procedure "spectcl::startUp" line 16)
    invoked from within
"spectcl::startUp"