Getting control of the main thread in windows c++ app

WM_CALLBACK = WM_APP+1

// Subclass the edit control.
wpOrigEditProc = (WNDPROC) SetWindowLong(hwndEdit, GWL_WNDPROC, (LONG)EditSubclassProc);

// Remove the subclass from the edit control.
SetWindowLong(hwndEdit, GWL_WNDPROC, (LONG)wpOrigEditProc);

VOID CALLBACK Function(
HWND hwnd,
UINT uMsg,
UINT_PTR idEvent,
DWORD dwTime
)
{
  // stuff
}

SetTimer(hWnd, event, 0, Function);