print #handle, "when event eventHandler"

This tells the window to process mouse and keyboard events. These events occur when a user clicks, double-clicks, drags, or just moves the mouse inside the graphics window. An event can also be the user pressing a key while the graphics window or graphicbox has the input focus.  This provides a really simple mechanism for controlling flow of a program which uses the graphics window.

Whenever a mouse event is trapped, Just BASIC places the x and y position of the mouse in the variables MouseX, and MouseY. The values represent the number of pixels in x and y the mouse was from the upper left corner of the graphic window display pane.

Whenever a keyboard event is trapped, Just BASIC places the value of the key(s) pressed into the special variable, Inkey$.

If the expression print #handle, "when event" is used with no branch label designation, then trapping for that event is discontinued.  It can however be reinstated at any time.

Events that can be trapped - names are case sensitive:
      leftButtonDown	- the left mouse button is now down
      leftButtonUp     	- the left mouse button has been released
      leftButtonMove	- the mouse moved while the left button was down
      leftButtonDouble	- the left mouse button has been double-clicked
      rightButtonDown	- the right mouse button is now down
      rightButtonUp	- the right mouse button has been released
      rightButtonMove	- the mouse moved while the right button was down
      rightButtonDouble	- the right mouse button has been double-clicked
      middleButtonDown	- the middle mouse button is now down
      middleButtonUp	- the middle mouse button has been released
      middleButtonMove	- the mouse moved while the middle button was down
      middleButtonDouble  - the middle mouse button has been double-clicked
      mouseMove		- the mouse moved when no button was down
      characterInput	- a key was pressed while the graphics window has input focus

