Hover over Btn ??

For an assignment i need to have an image i can drag around the screen and when it is over my button(hovering over it) i need the button to change backgrounds. I've made it so the image can be dragged around the screen and i have it so when clicked the button changes backgrounds, but how can i make it so when the image hovers over the button the background changes?

any help would be greatly appreciated

var dragWindow = Ti.UI.createWindow({
    title: 'drag and drop',
    backgroundImage: '/images/board.png'    
})
 
// MODEL
var lastTouchPosition;
 
// VIEWS
var revolver = Titanium.UI.createView({
    backgroundImage: "/images/revolver.png",
    top: 190,
    left: 110,
    width: 100,
    height: 100
});
 
var rotationTransform = Titanium.UI.create2DMatrix();
 
// CONTROLLERS
revolver.addEventListener('touchstart', function(e){
    var touchPos = {x: e.x, y: e.y};
    lastTouchPosition = revolver.convertPointToView(touchPos, dragWindow);
});
 
revolver.addEventListener('touchmove', function(e){
    var touchPos = {x: e.x, y: e.y};
    var newTouchPosition = revolver.convertPointToView(touchPos, dragWindow);
 
    // Move revolver by difference between two touch positions
    revolver.top += newTouchPosition.y - lastTouchPosition.y;
    revolver.left += newTouchPosition.x - lastTouchPosition.x;
 
    lastTouchPosition = newTouchPosition;
});
 
var hoverBtn = Ti.UI.createButton({
    title: 'drop',
    height: platformHeight * 0.2,
    width: platformWidth * 0.2,
    center: {
        x: platformWidth * 0.5,
        y: platformHeight * 0.48,
    }
});
 
hoverBtn.addEventListener('hover', function(e){
    hoverBtn.backgroundSelectedImage = '/images/blood.png';
});
 
dragWindow.add(hoverBtn);
dragWindow.add(revolver);

I just realised the hoverBtn event listener should be 'click' instead of 'hover', sorry about that