Getting input from the mouse.
This program demonstrates how to get mouse input. The
first part of the test retrieves the raw mouse input data
and displays it on the screen without using any mouse
cursor. When you press a key the standard arrow-like mouse
cursor appears. You are not restricted to this shape,
and a second keypress modifies the cursor to be several
concentric colored circles. They are not joined together,
so you can still see bits of what's behind when you move the
cursor over the printed text message.