I too wish to know this. I have a checkbox "Select all" that when checked should select all the items in the associated list box. The only code snippet I can find to do this is;
sizeOfListBox = numel(get(handles.SelectAllCheckBox, 'String'));
set(handles.SelectAllCheckBox, 'value',1:sizeOfListBox);
but this only works in GUIDE as far as I understand and I get an *Undefined variable "handles" error. Should "handles" be defined somehow and of so, where?
The rest of my code is working fine, I can multi select items in the listbox with CTRL and the output is as expected.
Another workaround to select all items is to select the first item in the list then SHIFT-click the last item, vis a vis typical Windows behaviour.
