Designing the Graphical User Interface › Graphical Design Standards › Standardize Modality on Windows › Modeless Windows

Modeless Windows

Modeless processing allows access to more than one window without closing the active one first. This works well with unrelated objects.

These are sources of confusion with modeless dialogs:

• Two modeless windows displaying the same object can create havoc on the desktop and even cause data integrity problems or errors.
• If the user accidentally processes changes from two windows containing the same object, the later change would either wipe out the effects of the first or cause an error to occur if it is caught.
• There may be valid business reasons for needing to view different occurrences of the same object at the same time. For example, a user may need to compare multiple versions of a quote side by side.
• Another source for confusion is the implementation of implicit commit.
• If the user selects a row from a list and flows to a modeless detail window, makes changes, and then selects another row from the list, the changes are implicitly committed as long as no business rules are violated.
• If business rules are violated, the user is put into an awkward situation of answering validation checks before the change of focus can occur.

If there is a good case for modeless processing, guidelines should be set for processing considerations, such as the list window keeps track of which occurrences are open so the same occurrence cannot be opened twice.

Modeless processing is usually used for menu processing to flow between applications.

The primary windows attached to a menu are modeless. After a primary window is invoked, the user can click on another window selection on the menu to invoke another application's primary window. Then the two applications can run simultaneously, and the user can switch between them. However, within each window, the dialog traversed by the user would be modal.