Why do the popupmenus/ listbox disappear if i use pushbutton callback ?

I have GUI, which has few pushbuttons that loads some data into popupmenus and listbox When I click on pushbutton, to reset the content to empty, it makes the popupmenu /listbox disappear. why does it happen? how can I avoid it ?

[Walter Roberson]

Please do not close questions that have an answer.

Your question is not unclear: you are just asking to do something that cannot be done in MATLAB.

[Image Analyst]

If you're got your answer, and are all done, then you can "Accept" the answer (to give the answerer reputation points and let everyone know it's solved) rather than Close the question.

Answer 1

[Walter Roberson]

When you set the String property of the popup or listbox to empty, you need to set the Value property to [] at the same time, or else the Value will be greater than the number of strings and it will consider that an error and refuse to draw the box.

[VBBV]

when I do that I get a warning message Warning: 'popupmenu' control requires a scalar Value. Control will not be rendered until all of its parameter values are valid Still the popupmenus disappear.

[Walter Roberson]

Basically, you cannot have an empty popup. You can have an empty listbox though.