I suggest that you have a look at Writeup Formatting Tips which tells you how to format your questions. The bottom of the preview page has a quick guide to available tags and some handy links.

You will get a better response if your questions are well presented. At a minimum use <p> </p> pairs for paragraphs and <code> </code> for literal code or data blocks.

Your problem is this line.

my $frame = $mw->new_labelframe()->g_pack();
[download]

You are assigning the result of g_pack() to $frame, you need to split it into two lines.

my $frame = $mw->new_labelframe();
$frame->g_pack();

# Now this works
$frame->new_button();
[download]