Drag and Drop
This is not a bug, but just somehting that causes unnecessary confusion. In the drag and drop activity (not the drag the words, but the drag and drop), I suggest removing the ability to include a background image in the settings tab. Instead, simply keep the ability to add images in the Task tab. Adding images there (in the task tab) is much more flexible, allowing for easy resizing and re-placing. Here's the confusion: since there's exists the ability to add an image in the settings tab (and the tutorial instructs you to do so), you think that's where you should add your image/s. But when you do so, you find the image takes up the whole screen, and there's no room for your draggable elements - then you have to go back and play with your image so it has some white space, rsave.... and on and on with unneccessary work. When if you just add that/those image/s in the TASK tab, you have way more flexibility.