I'm trying to add prev and next button to a gallery

Question

I've found a free flash gallery which looks good for my need here: http://www.flashgallery.org/
The only problem is that the gallery doesn't have prev and next buttons for the full size images, so I'm trying to add them.
I've been able to add those buttons, but they only work if I don't click on a thumb, as I click on a thumb they stop working.
In the code there is a function called loadGImage which loads the full size images, originally that function accepted 2 parameters, I've added a 3rd one which store the current image's index inside an array, so that I can use my buttons to call that function with index+1 for next and index-1 for prev.
In addition to this I've added a variable which is updated everytime a full image is shown, that variable contains the image's index.
Clicking on thumb the buttons stop working because the current image's index turns to "undefined" so they can't pass a correct value to loadGImage.
I've checked the code of the gallery, but I can't find where is said to the thumbs to call loadGImage, if I'd found that code I could add the index parameter and my buttons would work.
I'm sure that the thumbs call loadGImage because I've put a trace() inside the function to see when it is activated.
Here you can find the source file of the gallery (plus some images to see how the gallery works)
http://www.fileden.com/files/2008/4/9/1858524/FlashGallery2.rar
The code commented using /*   */ is the code written by me.
Can you help me to find where the thumbs make the call to loadGImage?

Answer 1

The informations about the images are read from an XML file.
These variables will contain the informations
_root.description = new Array();
_root.small_image = new Array();
_root.big_image = new Array();
_root.total_images = 0;
This code creates the thumbs
function createSmall()
    _root.smallContainer.createEmptyMovieClip("smallImageContainer", 10);
    var _loc4 = 0;
    var _loc3 = 0;
    for (var _loc2 = 0; _loc2 < _root.small_image.length; ++_loc2)
        _root.smallContainer.imageContainer.attachMovie("smallImage", "smallImage_" + _loc2, 100 + _loc2);
        m = _root.smallContainer.imageContainer["smallImage_" + _loc2];
        m._x = _loc3 * 50;
        m._y = 0;
        m.imageContainer.loadMovie(_root.small_image[_loc2], 100);
        m.iData = Array();
        m.iData.big = _root.big_image[_loc2];
        m.iData.title = _root.description[_loc2];
        ++_loc3;
    } // end of for
    _root.smallImageContainer._x = 5;
    _root.smallImageContainer._y = 0;
} // End of the function
And this is how full size images are loaded
function loadGImage(title, bigImgURL)
    _root.bigImage.imageContainer.loadMovie(bigImgURL, 100);
    _root.bigImage.imageContainer._x = 0;
    _root.bigImage.imageContainer._y = 0;
    _root.title.text = title;
    //trace(bigImgURL);
} // End of the function
I've checked around the fla file, but I haven't found any code associated to the thumbs which says to call loadGImage, that's my problem, because the code itself is not hard to understand.