Drag to create a rectangle whose one corner is where you start dragging, and opposite corner is where you end dragging.
Drag to create an ellipse whose center is where you start dragging, and is circumscribed in a rectangle with the same center and whose corner is where you end dragging.
Click to create a text element centered where you clicked.
Drag to create a straight line starting and ending where you start and end dragging.
Drag anywhere to move the currently selected element around in the canvas. To change which element is moved, select a different element in the list on the right.
Draw some stuff, then drag the slider to the end and select some elements in the list on the right and change some of the properties, then press Play to watch the change in those properties be smoothly animated!