This is certainly an unpleasant limitation. This is my first foray into appdesigner after being very familiar with creating programmatic GUIs using classes. The uneditable constructor and component initialisation functions will certainly take me some getting used to. In GUIDE I am used to passing input arguments in and using them to initialise sliders etc within the OpeningFcn.
My solution to the problem of not being able to pass input arguments to the constructor will likely be to create a 'named constructor' as a public static function, e.g.
methods ( Static, Access = public )
function app = create( someStuff, someOtherStuff )
app = MyApp;
app.someStuff = someStuff;
initialiseSlider( app, someOtherStuff );
and then launch the app as e.g.
It still means that the app is created before you can assign any of your properties or setup slider components based on inputs, but hopefully that will not represent a problem.
I hope appdesigner evolves to allow more standard class usage though. I understand why some of the code is locked to stop people screwing up the app by adding code that doesn't make sense, but for people who know what they are doing it is frustrating to have to use workarounds in code design.
Annoyingly the 'coding alerts' equivalent of M-Lint are very simplistic too. I get an alert saying I should use 'app' as the first argument to this create function even though it is in a Static methods block!