How to use DrawerJs
Stack Shapes
You can stack shapes and adjust their layering.
Imagine you have two shapes in the following order and you want to bring the blue rectangle in front of the yellow circle:

Select the blue rectangle and open the context menu by right-clicking the shape.
On touch devices, you can open the context menu by long-pressing the shape.
Now select Bring forward to move the shape one layer more to the front.

Now the blue rectangle is in front of the yellow circle.

In case you have stacked multiple shapes and want to bring the selected rectangle to the topmost position, you can quickly do so by selecting Bring to front.
Similarly, you can send a shape further back by using Send backwards and Send to back.