Overview
About Connections

Event-to-property connections
An event-to-property connection updates the target property whenever the source event occurs. An event-to-property connection appears as a unidirectional dark green arrow with the dark blue point to the target in the Connection Editor. The target property must be writable; otherwise, you cannot make the connection.

Event-to-method connections
An event-to-method connection calls the specified method of the target object whenever the source event occurs. An event-to-method connection appears as a unidirectional dark green arrow with the arrowhead pointing to the target in the Connection Editor.

Often much of an application's behavior can be specified visually by causing a method of one component to be invoked whenever an event is signalled by another component. For example, you might invoke the Сlose method on a TFrame component when the OnClick event is signalled by a button (this happens when the user clicks the button).

The some connections requires parameter. You can provide parameters through a parameter connection. For more information, see the information below.

Parameter connections
In most cases, when a connection needs a parameter, a parameter connection supplies an input value to the target of a connection by passing either the value from a constant, component property or the event parameter.

The original connection is always the source of a parameter connection; the source feature is the parameter itself.