Add a menu item and corresponding dialog fragment to select a default background color (add an appropriate material design vector icon)
Add a menu item to select a background color (or a background image) as the base on which to draw. Clearing the entire image should return the background to the default background color.
BONUS Allow the user to draw either rectangles or ovals or add an image - choose one. Allow the user to choose filled or hollow shapes, line thickness, fill color, etc.