use Tk;

my $top = new MainWindow;
my $c = $top->Canvas()->pack();
my ($x,$y);

# left mouse-button -> create text
$top->bind('<1>' => [\&click_left, Ev('x'),Ev('y')]);
# shift and left mouse-button -> edit text
$top->bind('<Shift-Button-1>' => [\&edit, Ev('x'),Ev('y')]);
# right mouse-button -> move the text
$top->bind('<3>' => [\&move_it, Ev('x'),Ev('y')]);

MainLoop;

sub click_left {
	my $e = shift;
	($x,$y) = @_;
	my $t = $top->Toplevel();
	my $entry = $t->Entry()->pack();
	$entry->focus();
	$t->bind('<Return>' =>sub{
		my $text = $entry->get();
		$c->createText($x,$y,-text=>$text);
		$t->destroy();
	});
}

sub move_it {
	my $e = shift;
	($x,$y) = @_;
	my $id = $c->find('closest',$x,$y);
	$top->bind('<Button3-Motion>' => [\&move, Ev('x'),Ev('y'),$id]);
}

sub move {
	my ($e,$xm,$ym,$id) = @_;
	my $dx = $xm - $x;
	my $dy = $ym - $y;
	($x,$y) = ($x+$dx, $y+$dy);
	$c->move($id,$dx,$dy);
}

sub edit {
	my $e = shift;
	($x,$y) = @_;
	my $id = $c->find('closest',$x,$y);
	my $text = $c->itemcget($id,'text');
	my $t = $top->Toplevel(-title=>"edit");
	my $entry = $t->Entry()->pack();
	$entry->insert(0,$text);
	$entry->focus();
	$t->bind('<Return>' => sub {
		my $text = $entry->get();
		$c->delete($id);
		$c->createText($x,$y,-text=>$text);
		$t->destroy();
	});
}