Zoom GUI in fltk backend

[John W. Eaton]

On 21-Jul-2009, Shai Ayal wrote:

| Before I submit a changeset, I'll wait a bit to see if anyone else has
| any input on which buttons to use for what.
| Anyone have any more suggestions?

I don't have any strong preferences about how it should work, but I do
think it would be good to have a way to zoom other than the scroll
wheel (or similar functionality from a mouse pad).

Would you like for me to commit your earlier patch now?

jwe