Open Appearance 

Open appearance is most commonly used for an embedded object, but it can also apply in other situations where the user opens an object in its own window. To indicate that an object is open, display the object in its container's window overlaid with a set of hatched 45-degree lines drawn every four pixels.

An object with an open appearance

If the opened object is selected, display the lines by using the system highlight color. If the opened object is not selected, display the lines by using the system's setting for window text color.