The 'onChange' callback

Event number: 23
Generated for: Combo, Edit, RichEdit, Document, Scroll, Selector, Splitter, Spinner, Trackbar, Grid

The onChange callback is generated when the text of an Edit, Combo, RichEdit or Document object has changed. This may be either because the user has typed something, or because your application has changed the text under program control. Generally, in your onChange callback handler you will read the text property of the object, and take action according to the new value (for example, disable the OK button if the text is not currently valid). Note that the onChange callback will be triggered every time the user types when the object concerned has focus. If you wish to validate the user's input only when it is complete, it is better to do this by means of an onUnfocus callback.

For a Scroll, Spinner or Trackbar control, the onChange callback is generated when the user changes the control's value. For a Splitter, it is invoked when the user moves the Splitter so that the attached controls are re-sized. For a Selector, it is invoked when the user selects a different Page.

For a Grid object, the onChange callback is triggered when the user has finished editing a cell. You can use it to validate the new cell contents, or to recalculate other cells in the Grid. The event-specific parameters in ⎕EV are (in index origin 1):

    ⎕EV[6]    Row number of the edited cell
    ⎕EV[7]    Column number of the edited cell
    ⎕EV[8]    Flag to indicate whether the contents were valid