You can now flip sprites horizontally or vertically. The aeroplane in this HTML animation only uses one image. When the plane flies in the opposite direction it is simply the same aeroplane image flipped horizontally. To flip an image in the editor, simply right click the item and choose 'Flip Horizontal/Vertical' or drag a selected sprite to resize it.
The animation also shows a smooth loop the loop. This makes use of the ability to rotate a sprite around a point.