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# PropagateIntervalChange()

## Definition

In an **NTWindow**, **PropagateIntervalChange()** sends an interval to other windows with the same Interval Linking color configured.

* A public BarsPeriod property must be defined in order to use **PropagateIntervalChange()**, as in the example below.
* For a complete, working example of this class in use, download the framework example located on our [Developing AddOns Overview](/developer/desktop-sdk/guides/educational-resources/addon-development-overview/developing-add-ons).

## Examples

```csharp
// This custom method will be fired when an interval selector in a custom NTTabPage changes intervals
private void OnIntervalChanged(object sender, BarsPeriodEventArgs args)
{
   if (args.BarsPeriod == null)
       return;

   PropagateIntervalChange(args.BarsPeriod);
}

```