ArcGIS Pro 2.6 API Reference Guide
ElementStyleChangedEvent Class
Members  Example 

ArcGIS.Desktop.Layouts.Events Namespace : ElementStyleChangedEvent Class
Occurs when an Element style is changed.
Object Model
ElementStyleChangedEvent ClassSubscriptionToken ClassSubscriptionToken Class
Syntax
Remarks
This event is specific to changes to an element's style. For listening to general changes to the element's properties, use ElementsUpdatedEvent instead. Reference ElementStyleChangedEventArgs to get a list of arguments.
Example
//Report the event args when an element's style is changed.

ArcGIS.Desktop.Layouts.Events.ElementStyleChangedEvent.Subscribe((args) => 
{
  var elements = args.Elements;
  string elemNames = "null";
  if (elements != null && elements.Count() > 0)
  {
    elemNames = string.Join(",", elements.Select(e => e.Name).ToList());
  }
  System.Windows.MessageBox.Show("ElementStyleChangedEvent:" +
  Environment.NewLine +
  "   arg Elements: " + elemNames.ToString() +
  Environment.NewLine +
  "   arg Layout: " + args.Layout.Name);
});
Inheritance Hierarchy

System.Object
   ArcGIS.Core.Events.EventBase
      ArcGIS.Core.Events.CompositePresentationEvent<TPayload>
         ArcGIS.Desktop.Layouts.Events.ElementStyleChangedEvent

Requirements

Target Platforms: Windows 10, Windows 8.1, Windows 7

See Also

Reference

ElementStyleChangedEvent Members
ArcGIS.Desktop.Layouts.Events Namespace