Here is the seventh example of the next release of PortablE:
Example 7: ToySketch.e
Someone wanted to know how to handle mouse input, so this example is a very simple drawing program, in 79 lines of E code.  (It could have been even smaller, but I got carried away adding features!)  I think you could have great fun expanding this into a fairly fully-featured drawing program... the only real draw back being that at the moment you won't be able to save the picture (I need to add a feature to the cGfx module to allow this - if you really want this then let me know & it might make it into the next Preview release!).