You can make drawings with Breakdown Notes. While it's not meant to make the most impressive paintings, it can be usefull to draw your own line segments or shapes.
If you have a touchscreen, you can use a stylus (or your finger) to draw. If you don't have a touchscreen, you can draw using the mouse. For both, you will first need to enter "draw mode".
To enter draw mode, just click and hold shift, then control. This should change your cursor. You can also enable draw mode from the "Drawing" menu. Just toggle the button. Now you can use your mouse or a stylus to draw on the map. To exit draw mode, just hit the escape key, or press the toggle button in the draw menu again.
To exit, just press escape, or the toggle button in the draw menu. Now you can position, resize, or style the drawing to your liking.
Normally, when you enter draw mode, all of the strokes you draw in one session (from Entering until exiting draw mode) will be seen as one drawing. That means every you drew will have the same stroke and color.
However, if you want to start a new drawing without having to exit and enter the draw mode, you can simply press shift. Also, changing the color or pencil size while in draw mode, will start a new drawing. To change the color or stroke of what you just drew, you will have to exit draw mode first.