Fill the callback functions of the pushbuttons.
The code for button left to right will include for example:
cList1 = get(hList1,'String');
nSelection = get(hList1,'Value');
cList2 = get(hList2,'String');
cList2 = [cList2 cList1(nSelection)];
set(hList2,'String',cList2);
I assume, you will add some comfort functionality, like sorting the list, preserve actual selection etc.
Btw - I do not know anybody in large scale GUI generation using GUIDE for final code. IMHO creating the GUI by code gives you a better basis for coding the functionality.
