I'm just having trouble coming to grips with this issue. At the moment, I'm trying to figure out how to implement a widget base class that can be sub-classed by either a QWidget-based class or a QGLWidget-based class. I can't figure out how to implement such a structure . Here's the problem:

Qt Code: 
  1. .
  2.                   +-----------------+
  3.                   | Abstract Base   |
  4.                   |     Class       |
  5.                   +-----------------+
  6.                         /    \
  7.                        /      \
  8.                       /        \
  9.                      /          \
  10.    +-----------------+          +------------------+
  11.    | QWidget-based   |          | QGLWidget-based  |
  12.    |      class      |          |      class       |
  13.    +-----------------+          +------------------+
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The abstract base class would include signals and slots that its sub-classes would implement. This creates a problem. If I were to say that the abstract base class inheritted QWidget, I can make the QWidget subclass work, but not the QGLWidget. If I were to say that the abstract base class inheritted QGLWidget, I can make the QGLWidget subclass work, but not the QWidget subclass. If I were to simply make the abstract base class inherit QObject, neither would work. Any idea how to resolve such a thing?

I can't get rid of all reference to a QObject ancestor because I require the virtual signals and slots inherittance.