The Shape tool
The shape tool is accessed by pressing 6 or by clicking the shape on the tool bar. By default, the selected shape is an arrow:
Clicking the two circular arrows will bring up the tool menu for shapes, allowing a new shape to be selected from the library:
When a shape is selected will then be able to place it while having control over the final proportions and size. If you want to draw a shape with fixed proportions, then hold shift and place the shape:
Draw filled shapes
The tick box will change the shapes library to filled in shapes.