mouse button and key press callbacks in the fltk backend

[John W. Eaton]

On 13-Apr-2010, Shai Ayal wrote:

| I just pushed http://hg.savannah.gnu.org/hgweb/octave/rev/9cdd6c8c05a4 which
| implements mouse and keyboard callbacks for the fltk backend.
| 
| The following figure callbacks should now be functional:
| windowbuttonupfcn,
| windowbuttonmotionfcn,
| windowbuttondownfcn,
| keyreleasefcn,
| keypressfcn
| In addition, the currentpoint property for figure and axes objects is
| updated with the mouse position:
| 
| As a demonstration for the use of these properties and callbacks I
| implemented the ginput function for the fltk backend.

Nice!

We should have an entry for this in the NEWS file and the concept of
graphics callbacks (and specifically these features) should be
documented in the manual before the next release.

jwe