This enumeration is used by System.Security.Permissions.UIPermission.
Users can use all windows and user input events without restriction.
Users cannot use any windows or user interface events. No user interface can be used.
Users can only use UIPermissionWindow.SafeSubWindows for drawing, and can only use user input events for user interface within that subwindow. Examples of UIPermissionWindow.SafeSubWindows are a System.Windows.Forms.MessageBox, common dialog controls, and a control displayed within a browser.
Users can only use UIPermissionWindow.SafeTopLevelWindows and UIPermissionWindow.SafeSubWindows for drawing, and can only use user input events for the user interface within those top-level windows and subwindows.