Adding a Keyboard Interface

Now we have another problem. When the menu contains text, Windows automatically adds a keyboard interface. You can select a menu item using the Alt key in combination with a letter of the character string. But once you put a bitmap in a menu, you've eliminated that keyboard interface. Even if the bitmap says something, Windows doesn't know about it.

This is where the WM_MENUCHAR message comes in handy. Windows sends a WM_MENUCHAR message to your window procedure when you press Alt with a character key that does not correspond to a menu item. We need to intercept WM_MENUCHAR messages and check the value of wParam (the ASCII character of the pressed key). If this corresponds to a menu item, we have to return a long integer back to Windows where the high word is set to 2 and the low word is set to the index of the menu item we want associated with that key. Windows does the rest.