use Tk; my $mw = MainWindow->new( ... options ... ); my $this = $mw->ThisWidget -> pack ; my $that = $mw->ThatWidget; ... MainLoop;
Tk::MainWindow is a special kind of Toplevel widget. It is the root of a widget tree. Therefore "$mw->Parent" returns "undef".
The default title of a MainWindow is the basename of the script (actually the Class name used for options lookup, i.e. with basename with inital caps) or 'Ptk' as the fallback value. If more than one MainWindow is created or several instances of the script are running at the same time the string " #n" is appended where the number "n" is set to get a unique value.
Unlike the standard Tcl/Tk's wish, perl/Tk allows you to create several MainWindows. When the last MainWindow is destroyed the Tk eventloop exits (the eventloop is entered with the call of "MainLoop"). Various resources (bindings, fonts, images, colors) are maintained or cached for each MainWindow, so each MainWindow consumes more resources than a Toplevel. However multiple MainWindows can make sense when the user can destroy them independently.