This list-notation syntax of OO-Perl looks more similar to the
Tcl program, however list-notation has no stacking of calls. Your programs
will be more verbose because of 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.