It would be nice if the gallery had a TemplateFill property for on hover (TemplateFillHover). Currently we can accomplish a selected color change with an if statement to set selected item to a different color, but there is no way to set a hover property for the TemplateFill of a gallery item. This would be invaluable for Components relating to Navigation. Pop and Push transitions are not really sufficient or easy to recognize for an end user when hovering over, but a color change on hover would be.
Ideally, there would also be a TemplateFill for the selected item to avoid the if statement, but at least this is an easy work around currently.