function add_buttons( num, offset, suffix ){
	if(   offset + num > 1   ){
		for( var i = offset; i < ( offset + num ); i++ ){
			document.write( '<span class="tab_num" onmouseout="this.style.cursor=\'default\'" onmouseover="this.style.cursor=\'pointer\';" onclick="this.style.background=\'#ecf5e6\'; tabs' + suffix + '[curr_tab_i' + suffix + '].style.visibility = \'hidden\'; tabs' + suffix + '[' + i + '].style.visibility = \'visible\'; curr_tab_i' + suffix + '=' + i + ';">' + ( i + 1 - offset ) + '</span>' );
		}
	}
}