Fixed button mapping. Was returning the physical button instead of

the logical button, but XTest wants the logical button.  Apparently,
the XTest implementation on my mac laptop has it backwards.

lib/platform/CXWindowsScreen.cpp

@@ -1740,7 +1740,7 @@ CXWindowsScreen::mapButtonToX(ButtonID id) const
 	}
 
 	// map button
-	return static_cast<unsigned int>(m_buttons[id - 1]);
+	return static_cast<unsigned int>(id);
 }
 
 void