To implement category, draw to buttons (or 1000) and on key frame one:

/////// remove all //////////

addEventListener(Event.ENTER_FRAME,myEnterFrame);
function myEnterFrame(event:Event) {
if ( _gallery ){
_gallery.removeEventListener(ScGallery.ON_HIDE, onGalleryHide);
removeChild(_gallery);
_gallery =null;
}
}
////////////// end remove all /////////////////

/////////////// buttons //////////

unu_btn.buttonMode = true;
unu_btn.addEventListener(MouseEvent.CLICK, Load_Gallery);

function Load_Gallery(event : MouseEvent) : void {

removeEventListener(Event.ENTER_FRAME,myEnterFrame); // STOP THIS LISTENER
_gallery =new ScGallery(new Rectangle(0,0,800,600));
_gallery.addEventListener(ScGallery.ON_HIDE, onGalleryHide);
addChild(_gallery);
_gallery.loadData(”xml/portraits.xml”);

}
// repetate the code for button two //

doi_btn.buttonMode = true;
doi_btn.addEventListener(MouseEvent.CLICK, Load_Gallery2);

function Load_Gallery2(event : MouseEvent) : void {
removeEventListener(Event.ENTER_FRAME,myEnterFrame); // STOP THIS LISTENER
_gallery =new ScGallery(new Rectangle(0,0,800,600));
_gallery.addEventListener(ScGallery.ON_HIDE, onGalleryHide);
addChild(_gallery);
_gallery.loadData(”xml/data.xml”);

}
///////////////////////////////////////////////////////////////

Duplicate the data.xml and rename it for each buttons, is pretty self explanatory.

Have a nice day,