use strict;
use Tcl::Tk qw(:widgets :perlTk);

my $mw = MainWindow->new;
my $int = $mw->interp;

$int->Eval("package require BLT;namespace import blt::*");

my $bltgraph = $int->awidget(qw/graph .g -title My_graph/);

$bltgraph->pack;

my $marker;
$bltgraph->elementCreate(qw/line1 -symbol triangle/,
  -xdata=>[map{0.2*$_}0..9],
  -ydata=>[map{$_*$_}0..9],
);
$bltgraph->markerCreate( 'window',
  -window => $bltgraph->Button(-text=>'Window marker',-command=>sub {
    $bltgraph->markerConfigure($marker,
       -rotate => $bltgraph->markerCget($marker,-rotate)+15);
  }),
  -coords => [1, 60],
);
$bltgraph->markerCreate( 'text',
  -text => 'marker text',
  -rotate => 30, -font =>'Helvetica 30',
  -coords => [0.5, 60],
);
$marker = $bltgraph->markerCreate( 'text',
  -text => 'marker text2',
  -rotate => -15, -font =>['Helvetica', 30],
  -coords => [0.5, 20],
);

MainLoop;