## OnChanged

### Description

This callback is fired when the user changes a parameter value in a property page control (for example, by selecting an item from a drop-down list, changing the value in a field, or selecting a check box).

Note that changing the contents of a list box (setting PPGItem.UIItems property) does not trigger an OnChanged callback.

To access the property page from the callback code, use the PPG object.

### Applies To

Custom Properties implemented in a scripting language.

### Syntax

    function <property_name>_<parameter_name>_OnChanged()
    {
            ...
    }

    def <property_name>_<parameter_name>_OnChanged():
            ...

    Function <property_name>_<parameter_name>_OnChanged()
            ...
    End Function

    sub <property_name>_<parameter_name>_OnChanged
    {
            ...
    }

<property_name> is the name specified in the call to PluginRegistrar.RegisterProperty, with any spaces converted to underscores. For example, if you register a property with the name "My Property", the callback function names start with "My_Property".

### Examples

    // Enable/disable a text box based on the state of a check box
    function MyProperty_MyCheckbox_OnChanged( )
    {
     var bFlag = PPG.MyCheckbox.Value;

     // If the check box is cleared, disable the text box
     if ( bFlag == false )
     {
         PPG.MyTextBox.ReadOnly = true;
     }
     else
     {
         PPG.MyTextBox.ReadOnly = false;
     }

     PPG.Refresh()
    }

### See Also

- Define
- DefineLayout
- OnClicked
- OnClosed
- OnInit
- OnTab
- PPGEvent
- Property Callbacks