Inserting code into Gnumeric

[Ser Nam Lim <sernam cs umd edu>]

Hi,

If I want to add some code such that I can add a button on the top panel
of the Gnumeric application and clicking on the button can result in the
execution of some function that I have written, what are the various
places that I need to modify and add?

I know that new functions can be added via python plugin but how can I
change the graphical appearance of the Gnumeric application to include an
extra button to invoke the new function? Also, if I don't want to use
python to add a new function, is there any other way for me to do it?

Any help will be greatly appreciated. 

Regards,
Ser Nam