What 2D GUI Foundation do you use?

Zmee writes: I am looking to build a 2D application for personal use and I will need to use a canvas to paint custom objects. I am trying to determine what foundation to use and have not located a good side-by-side comparison of the various flavors. For reference, I need the final application to work in Windows; Linux is preferred, but not required. I have looked at WPF, Qt, OpenGL, Tcl/Tk, Java's AWT, and others. I have little preference as to the language itself, but each of the tutorials appear to require significant time investment. As such, I am looking to see what the community uses and what seems to work for people prior to making that investment.