I built a small GUI using Tkinter. The GUI features, among some other elements, three buttons. These buttons serve to open a dystem dialog and select certain data-files etc. One of the three buttons is a 'Go' button that runs the underlying data-processing.
When running the .py script the GUI works fine. However, after creating a developer app in alias mode using Py2App the buttons have become invisible! They're still there and usable, but invisible until interacted with.
How can I prevent this from happening?
I was stuck in your exact situation for quite some time. When I ran my tkinter script, it worked perfectly and all the buttons showed up, but once I packaged it, the buttons stopped showing up (They were still there but you couldn't see them). After a long time of trying random things, I found out how to make the buttons and their text show up again. Simply resize the window. Even a difference of 1 or 2 pixels does the trick. I have not yet found a way to PREVENT this issue, but at least this makes the app look right. 
Please reply if you figure out a solution to prevent this!
Good Luck!
Tkinter GUI buttons become invisible after creating app using Py2App