18.104.22.168.3 User Interface Messages
Every printer driver is responsible for displaying two custom user interfaces: one for document properties and one for printer properties. Because a custom UI is difficult to negotiate over a network, the virtual server printer driver exposes its own custom UI by delegating these requests to the client printer driver. The client printer driver contains the actual implementation of these interfaces. The following two figures show a typical packet exchange for displaying UI. In the first figure, the UI is opened and closed by the user on the client machine. In the second figure, the UI is displayed on the client but then canceled by the server. This sequence is typical in situations that cause the UI to disappear, such as the locking of the user's desktop.
Figure 4: Open and close document properties UI
Figure 5: Open and cancel document properties UI