🚀 go-pugleaf

Thanks for the responses.  Several hours after posting the original question,
I got back home and tried out a hunch and it turned out to be mostly
correct.  Michael Harris pointed out the rest of the solution.

The scenario:
  In my application, I want to capture the position of the mouse when
  the user clicks a button.  If I simply record the position
  parameters and return (MRESULT)0, which indicates that I've
  processed this message, the frame for the entire application loses
  the focus, which means that I can't use the ALT-F, etc keystrokes to
  access the menus.

The solution:
  Call DefWindowProc() (whatever the default window message handler is
  called ) *BEFORE* you fully process the WM_BUTTON1DOWN message.

For example, this might look like this: (details escape me at the
present)

  ...
  switch(...) {
      case ... :

      case WM_BUTTON1DOWN:
          defResult = DefWindowProc(hwnd,msg,mp1,mp2);
	  savedPointerPos.x = SHORT1FROMMP(mp1);
	  savedPointerPos.y = SHORT2FROMMP(mp1);
	  return defResult;
      case ... :
      ...
  }
  ...

This ordering guarantees that the application window will retain the
focus (including coming to the foreground) and that you will also be
able to process the mouse button click message.

Pete