Volatile

A window object with VOLATILE flag should only be visible if the date to be displayed also exists, otherwise it is automatically hidden by FillWindow or AdjustView.

When is data missing in an object?
This is possible

• in the case of a non-existent slot
• if a pointer or a function in the access path returns the value NULL
• or if the kth element of a collection, which has fewer than k elements, is accessed (this also results in NULL).

For example, a function can be used to decide at any point in the access imprint whether it should be followed up or not.

Often you want to show and hide other window objects - e.g. the prompt belonging to an input field - as well. For these objects simply the VOLATILE flag with the same identifier - which here identifies a group of logically related window objects - must be set.

If a window object refers to a 'normal' data member of a model object, the VOLATILE flag is without function.