[Overview][Constants][Types][Classes][Procedures and functions][Variables][Index] | Reference for unit 'Controls' (#lcl)

# TControl.Changed

Performs actions needed when the value for the control has been changed.

## Declaration

Source position: controls.pp line 1497

`protected procedure TControl.Changed;`

## Description

In TControl, Changed calls Perform to post a CM_CHANGED control message to the message processing loop. The Parent control, which provides the window handle, receives the message in its CMChanged method and calls its WindowProc processing loop.

Changed may be overridden or reimplemented in descendent classes to perform actions needed in the implementations for the controls. For instance, triggering OnChange or other notification events.

Changed is called when properties for the control, especially its value, have been modified.

## See also

TControl.CMChanged |  | Handles CM_CHANGED control messages for the control.
TControl.Parent |  | The control within which the control is shown.
TControl.Perform |  | Calls a message handler directly, bypassing the message queue.