updating one popup menu instantly after a string is chosen in another popup menu

I have three popup menus, the first which is to select a country. I want to set that when a country is chosen, the second popup menu will automatically go to the cities for that country . and after the city is chosen the third popup menu will fill with the airports of that city. I want all these changes at the same menu, and without the need of using refresh pushbutton. is that possible?

I would really appreciate if you help me with my problem.

Answer 1

[Walter Roberson]

Yes, each popup is a uicontrol(), and each uicontrol may have a callback function. The action of one callback can be to set() the 'String' of another uicontrol so that it has a different selection of popup entries.