How to call another GUI and let the rest code in GUI1 wait until GUI2 finishes executing?

Hello, I'm currently working on a GUI, which has a function of reading a certain column of an excel file. There are altogether two GUIs, GUI1 and GUI2. When users click the pushbutton 'read excel' in GUI1, GUI2 shows up, where users can input the column label(letter: A,B,C...) that needs to be read. By clicking the button 'OK' in GUI2 the results will be transferred back to GUI1 and display in a listbox in GUI1. But I have trouble with the proceeding sequence, so first here is my code(incomplete):

GUI1

function excel_reading_Callback(hObject, eventdata, handles)
global EX_RESULTS

assignin('base','EX_RESULTS',EX_RESULTS);

%open GUI2
GUI2
% fill in listbox with reading results
Fields_of_EX_Results=getappdata(GUI2,'Fields_of_EX_Results');
set(handles.results_listbox, 'String', fieldnames(Fields_of_EX_Results));  %%%Possible error, since Fields_of_EX_Results only exists after OK_Callback in GUI2 executes

GUI2

function OK_Callback(hObject, eventdata, handles)
global EX_RESULTS
%the users can input the column label in GUI2 and the corresponding column will be read
% and saved in a structure called EX_RESULTS
%by using setappdata and getappdata the results can be transferred back to GUI1

Now i got this error message, because in the excel_reading_Callback in GUI1, the 'set(handles.results_listbox....' can only execute after OK_Callback in GUI2 was finished executing and all results are store in EX_RESULTS. So how can I arrange the proceeding sequence of the code? So that the rest of code in GUI1 can wait until GUI2 is finishing executing? Or can I just use 'set' in GUI2 to set the results to listbox in GUI1?

THX in advance

Answer 1

[Walter Roberson]

After calling GUI2, call uiwait() with no arguments. Then in GUI2, when it is ready, call uiresume() with the handle of GUI1

And try to avoid global!

http://matlab.wikia.com/wiki/FAQ#How_can_I_share_data_between_callback_functions_in_my_GUI.3F