Dialog Box WM_PAINT problem

[VictorN]

... what is the most appropriate way of declaring variables that I want to be accessible in both callback functions (WinProc and DialogProc) or both in WinMain and WinProc? Should I always use global variables in these cases or perhaps make a class in the header and put them there as static? How do professionals do this?

Sorry. I cannot answer...
I use MFC, so I don't have such a problem.