$(document).ready(function(){
    is_block = false;
    $(".chanls .dwarr a").click(function(){
        var channels_block_height = Number($("#channels_block").attr("items") * 78);
        var str_channels_block_mt = $("#channels_block").css("margin-top");
        var channels_block_mt = Number(str_channels_block_mt.substr(0, str_channels_block_mt.length - 2));
        if ((channels_block_height - 312 + channels_block_mt > 0) && (!is_block)) {
            is_block = true;
            $("#channels_block").animate({"marginTop": "-=78px"}, "500", function(){
                is_block = false;
            });
        }
        return false;
    });
    $(".chanls .uparr a").click(function(){
        if (($("#channels_block").css("marginTop") != "0px") && (!is_block)) {
            is_block = true;
            $("#channels_block").animate({"marginTop": "+=78px"}, "500", function(){
                is_block = false;
            });
        }
        return false;
    });
});