Windows and forms

Programs manipulate window and form objects to define display areas controlled by interactive statements. Once created, the abstract user interface (AUI) tree contains a definition of these objects.

The OPEN WINDOW statement creates and opens a new window. The runtime system maintains a stack of all open windows. When you execute this statement to open a new window, it is added to the window stack and becomes the current window. You can modify the window stack with the CURRENT WINDOW and CLOSE WINDOW statements.

The OPEN WINDOW ... WITH FORM statement should be used to open a window on the screen, load a compiled (.42f) form from disk into memory, and make it ready for use.

The forms are defined in text-based form specification files (.per). These form files are transformed by the fglform compiler to produce the runtime form files (.42f) that are deployed in production environments. The resulting (.42f) files are XML documents that describe the form elements, enabling portability across display devices. The XML file can also be written directly, or it can be generated or modified from your program at runtime with XML utilities.

You can design your form to group widgets in different sort of layout containers, define toolbars and topmenus, list containers, treeviews, data fields and buttons triggering actions in programs, etc.

The appearance of form objects can be standardized using presentation styles and default attributes for action views.

Different parts of a form can be handled simultaneously using interactive instructions in programs.