When an assembly uses Windows Forms (classes and interfaces from the ``++System.Windows.Forms++`` namespace) its entry point should be marked with the ``++STAThreadAttribute++`` to indicate that the threading model should be "Single-Threaded Apartment" (STA) which is the only one supported by Windows Forms.


This rule raises an issue when the entry point (``++static void Main++`` method) of an assembly using Windows Forms is not marked as STA.
