About creating new forms by extension

To keep the basic functionality and design of a form but customize it for your own needs, an effective option can be to create a new form based on the existing version. Windows client provides a means to do that, using the New Form Wizard.

When you select the option to Extend an existing form, the New Form Wizard allows you to create a copy of the original form, which you can then modify to your own needs.

The big advantage to creating a form with this option is that if/when changes are made to the original (parent) form, they automatically cascade to your extended form. This allows you to have a customized version of the form while at the same time keeping up with the latest changes to the original form on a selective basis.

The new form starts as an exact duplicate of the original form, but with all the components locked. The Form properties sheet indicates that it is an extension of an existing form with the Base Form Name property.

By default, all components, event handlers, variables, and scripts are inherited from the base form. These objects are all read-only by default, but you can unlock components and modify them as required. To do this for a selected component, set the From Base Form attribute in the Component property sheet to False, and then make your changes as with any other component.

You can also add new components and functionality to the form, according to your needs.

Any time that you want to see which objects on the extended form are inherited from the original (base) form and which are unique to your extended form or modified in your extended form, you can view this information in the Extended Form Details dialog box.

When a derived form is initially created, it shares the same collections with the base form. If you make any changes to a collection in the derived form, all collections from the base form are unshared. If you make changes on the collections of the base form, you must make these changes on the derived form as well.