WNDPROC cast error

Make WndProc static.

See Creating a Win32 Window Wrapper Class for details on one approach to creating a window class. Here's another approach: WNDPROC Thunks.

The trouble is this.

wc.lpfnWndProc = &Framework::WndProc;

A WNDPROC type of function pointer is expected.

typedef LRESULT (CALLBACK* WNDPROC)(HWND, UINT, WPARAM, LPARAM);

where CALLBACK indicates the calling convention used. It's a macro defined as

#define CALLBACK __stdcall

Framework::WndProc - as a member function uses the __thiscall calling convention (See Member Function Pointers for details).

If typedefed as a __stdcall it would look like this (not exactly but close enough)

typedef LRESULT (CALLBACK* Framework_WNDPROC)(Framework* this, HWND, UINT, WPARAM, LPARAM);

The signatures of the two types of function pointers don't match. The method form expects it's first argument to be a pointer to the object, but the window passes a HWND as the first argument. That creates a problem down the road. Declaring Framework::WndProc as static resolves this conflict because in effect it turns the object method into an ordinary stand alone function that internally references the object as a static variable.