@TK[expression] : Returns the string result of the Tk expression. For example, this will execute the Tk script test.tcl:
echo %@tk[source test.tcl]
Because of the way the Tk interpreter works, it is not possible for TCC to maintain a persistent interpreter after executing a Tk script. TCC will close the current Tcl/tk interpreter and create a new one the next time @TCL is executed.
See also @TCL.