About Events
 
These are a kind of message that RISC OS sends to applications
to tell them what is happening. For example, when a user clicks on
an icon, RISC OS sends a 'button click' event to the application.
When a user moves a window, an 'open window' event is sent to
the application.
 
In WimpBasic you connect a Procedure or Function to these events.
WimpBasic will then automatically call your routine when the event
is received.