Free Forms and Form Families

Forms are displayed on the screen either as free-standing forms or as a member of a form family.

A form can be displayed as a free standing form, for example by show !!form free. It then has no parent so it will not disappear when the form which caused it to be displayed is hidden.

When one form causes another form to be displayed, such as when a button with the FORM keyword is pressed or a gadget callback executes a show !!form command the result is a child form.

A form can have many child forms (and grandchildren) but a child form has only one parent - the form which caused the child form to be displayed. The nest of related forms is called a Form Family.

The Form Family exists just as long as the forms are displayed. If a form is already on the screen when it is shown, it is brought to the front of the display. If the child form is already in a Form Family it is transferred to the new parent.

If you press the OK button of a parent form, the system in effect presses the OK buttons on each of the child forms, 'youngest' first, invoking their OKCALL callbacks. The parent form and all child-forms are hidden and the Form Family then ceases to exist.

If you press the CANCEL button or use the window's CLOSE controls, the system in effect presses the CANCEL buttons of each of the child forms, 'youngest' first, invoking their CANCELALL callbacks, and all the forms in the Form Family are hidden.

The action of RESET and APPLY buttons does not affect family members.