How to share data between Multi Window GUI?

To have input arguments to a GUI. The mathworks page says to open the dialog box app into Code View. Then click App Input Arguments in the Editor tab. But I do not see this option in my appdesigner. Could you please help me? I have the screenshot of what I see:

[Rik]

Must it be an app? I have some experience with GUIs, but next to none with the App Designer. The few times I did open it, it seemed much more complicated than just whipping a GUI together with a figure.

[Goku]

It need not be, but I only have experience in the AppDesigner and I have already made quite a few apps on it. If the translation is easy i would not mind that.

[Rik]

It looks to me like the App Designer is like writing a class and with a figure it is like writing a function. I would say a 'normal' GUI is easier to program, but I have too little experience with App Designer to comment on how easy the transition is.

The most important thing is to only use GUIDE for the first raw sketch, but don't use the auto-generated code. uicontrol and guidata are your friends.

[Goku]

Thank you for your input! I will give that a try now.