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.
Syntax
Remarks
When it runs under UIPermissionWindow.SafeTopLevelWindows permission, your application:
Will show the DNS name or IP address of the Web site from which the application was loaded in its title bar.
Will display Balloon tool-tip when it first displays, informing the user that it is running under a restricted trust level.
Must display its title bar at all times.
Must display window controls on its forms.
Cannot minimize its main window on startup.
Cannot move its windows off-screen.
Cannot use the System.Windows.Forms.Form.Opacity property on System.Windows.Forms.Form to make its windows less than 50% transparent.
Must use only rectangular windows, and must include the window frame. Windows Forms will not honor setting System.Windows.Forms.Form.FormBorderStyle to None.
Cannot make windows invisible. Any attempt by the application to set the System.Windows.Forms.Control.Visible property on its System.Windows.Forms.Form objects to False will be ignored.
Must have an entry in the Task Bar.
Will have its controls prohibited from accessing the System.Windows.Forms.Control.Parent property. By implication, controls will also be barred from accessing siblings - i.e., other controls at the same level of nesting.
Cannot control focus using the System.Windows.Forms.Control.Focus method.
Will have restricted keyboard input access, so that a form or control can only access keyboard events for itself and its children.
Will have restricted mouse coordinate access, so that a form or control can only read mouse coordinates if the mouse is over its visible area.
Cannot set the System.Windows.Forms.Form.TopMost property.
Cannot control the z-order of controls on the form using the System.Windows.Forms.Control.BringToFront and System.Windows.Forms.Control.SendToBack methods.
These restrictions help prevent potentially harmful code from spoofing attacks, such as imitating trusted system dialogs.
Requirements
Assembly: mscorlib (in mscorlib.dll)
Assembly Versions: 1.0.5000.0, 2.0.0.0, 4.0.0.0