Progress
Programming
Handbook
Window-based Applications
Progress supports three types of interactive application:
- Single-window — Every interactive Progress application uses at least a single window. Typically, you use the static window provided by Progress, although you can create your own, instead, if you want to change any attributes set prior to realization. You can change any attributes of the static window that can be set after realization.
- Multi-window with non-persistent management — You can create additional windows for viewing or updating specific information using non-persistent procedures. In non-persistent procedures, you can use multiple windows to group related information or just to provide greater flexibility and more screen space. In a non-persistent environment, you must manage each window explicitly throughout the application. Also, you cannot easily manage multiple windows as copies or iterations of a single window. No matter how similar the definition of each window is to another, each window requires separate management code that must be integrated with the rest at every point in the application.
- Multi-window with persistent management — You can also create additional windows using persistent procedures. This technique allows you to have more than one copy of a like-defined window on the screen simultaneously, managed by the same application code. Managing multiple windows with persistent procedures affords far greater flexibility than using only non-persistent procedures.
Typically, a persistent procedure creates the window it controls when it executes. This window then remains on screen and available for input after the procedure returns from execution. Unlike windows created by non-persistent procedures, windows created in persistent procedures require little or no management by the main line of your application.
The essential management code for each window is contained in the persistent procedure that created it. Also, each time you execute a persistent procedure, it can create a completely new window that is a copy of others created by the same procedure. Each copy is managed by the same application code in its own procedure context. If you so design, your main-line application can interact with the windows of these persistent procedures through standard procedure triggers or internal procedures provided to the application by the persistent procedures.
NOTE: You can also create multiple windows using persistent triggers in a non-persistent procedure, but this is a less robust technique with more complicated window management requirements.As the single-window application is the default application style used throughout this manual, the following sections describe the two basic techniques of managing multi-window applications: non-persistent and persistent.
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