Why can't I launch my GUI with a listbox directly by opening the .fig file?

As soon as I close the Layout Editor and the .fig file of a GUI, and attempt to start the GUI directly by opening the .fig file, the listbox no longer displays its items and I get the error message

 Attempt to reference field of non-structure array 'handles'

Answer 1

[MathWorks Support Team]

The proper way to launch a GUI (other than 'activate figure' from the Layout Editor) is to call the application program file. For example, if you created a GUI named 'test' with GUIDE, you will generally have two files: test.fig and test.m. To launch this GUI execute:

test

from the MATLAB Command Prompt.

In your test.m file you have the following line:

fig = openfig(mfilename,'reuse');

which opens the figure file (in this case: test.fig).

If you try to launch the GUI by opening the test.fig file directly, MATLAB has no reference to the test.m file, where you have, for example, your callbacks. This file also is used to create a structure called 'handles', which is then used to store the handles to all the uicontrols in your GUI.