uimenu implementation, 2nd version

[John W. Eaton]

On 21-Oct-2010, Kai Habel wrote:

| Since I have seen some crashes in intermediate versions, it would be 
| nice if people regularly bulding octave on Mac and Windows could test 
| the changeset. I have attached a simple test file as well.

I didn't test it extensively (all I did was try your test function and
play with a few of the  buttons) but it seems to work for me.

Could you please do the following

  * remove the debugging print statements
  * change the commit message to be something more descriptive than
    [mq] uimenu (use -m "..." with hg qrefresh)
  * add a demo or two to the uimenu function.
  * add ChangeLog entries

and then check in your changes?

I will try to take another look at the callback problem soon.

Thanks,

jwe