var c_max_images=99;

function choose_gallery_pic(num,img_name,class_prename,caption) {

	obj = document.getElementById('mainpic');
	if (obj) {
	  obj.src=img_name;
	}
	for (i=1;i<=c_max_images;i++) {
      thumbid = 'thumb_' + i;
	  obj = document.getElementById(thumbid);
  	  if (obj) {
	    obj.className=class_prename + 'thumb';
	  }
	}
	thumbid = 'thumb_' + num;
    obj = document.getElementById(thumbid);
  	if (obj) {
      obj.className=class_prename + 'thumb_selected';
    }
    obj = document.getElementById('maincaption');
  	if (obj) {
      obj.innerHTML=decodeURIComponent(caption);
    }

}