This list-notation syntax of OO-Perl looks similar to the
Tcl program, however list-notation does not provide stacking of calls.
Your programs will be more verbose and need more variables in that
Naming of components is not required, which saves you from looking for
explanatory names for simple components in most cases.
MainWindow can be used in Perl/Tk on every spot where Tcl requires Toplevel:
the MainWindow is a more flexible object. On UNIX you can have more than
one under control in one program.