OK, really easy to fix it. Open source\oxylus\JuneGallery\ImageViewer.as, find the following two blocks of code and add the lines written in bold:
Code:
private function LftPress() {
data = prvNode();
LftOver();
}
private function RgtPress() {
data = nxtNode();
RgtOver();
}
Save the file, then open source/main.fla and republish the swf.