I have a class for displaying images, that is non-Qt for sufficient reasons. I wrap it in various QGLwidgets to create different photography apps. It has lots of control parameters, whose functions the app is not going to modify. The Qt object that creates the controls converts messages from those controls into calls to image display methods, using a global pointer to the display object.

Thus, the app does not need to worry about the image display API. But it is concerned with how the controls are presented to the user, and must place them in various dialogs according to its mission.

Is that clear enough?

Re the SignalMapper: Leaving aside that it does not return values from the controls themselves, it requires not one but two explicit connect calls per control group. My problem here seems to result from my trying to avoid having to write any connect calls. I believe that if I were willing to do that, I could use a QObject instead of a QWidget, and the screen flashing would likely go away.

--Tom