UTSL

 sub content_as_png {
    my ($self, $tab, $rect) = @_;
    $tab ||= $self->tab;
    $rect ||= {};
    
    # Mostly taken from
    # http://wiki.github.com/bard/mozrepl/interactor-screenshot-server
    my $screenshot = $self->repl->declare(<<'JS');
    function (tab,rect) {
        var browser = tab.linkedBrowser;
        var browserWindow = Components.classes['@mozilla.org/appshell/
+window-mediator;1']
            .getService(Components.interfaces.nsIWindowMediator)
            .getMostRecentWindow('navigator:browser');
        var win = browser.contentWindow;
        var body = win.document.body;
        if(!body) {
            return;
        };
        var canvas = browserWindow
               .document
               .createElementNS('http://www.w3.org/1999/xhtml', 'canva
+s');
        var left = rect.left || 0;
        var top = rect.top || 0;
        var width = rect.width || body.clientWidth;
        var height = rect.height || body.clientHeight;
        canvas.width = width;
        canvas.height = height;
        var ctx = canvas.getContext('2d');
        ctx.clearRect(0, 0, width, height);
        ctx.save();
        ctx.scale(1.0, 1.0);
        ctx.drawWindow(win, left, top, width, height, 'rgb(255,255,255
+)');
        ctx.restore();

        //return atob(
        return canvas
               .toDataURL('image/png', '')
               .split(',')[1]
        // );
    }
JS
    my $scr = $screenshot->($tab, $rect);
    return $scr ? decode_base64($scr) : undef
};
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Now i try to install mozrepl - if you or anybody has got some tipps on that. should i run

Hire a sysadmin, seriously