Window.Activated Event

public:
 virtual event WindowActivatedEventHandler ^ Activated;

// Register
event_token Activated(WindowActivatedEventHandler const& handler) const;

// Revoke with event_token
void Activated(event_token const* cookie) const;

// Revoke with event_revoker
Window::Activated_revoker Activated(auto_revoke_t, WindowActivatedEventHandler const& handler) const;

public event WindowActivatedEventHandler Activated;

function onActivated(eventArgs) { /* Your code */ }
window.addEventListener("activated", onActivated);
window.removeEventListener("activated", onActivated);
- or -
window.onactivated = onActivated;

Public Custom Event Activated As WindowActivatedEventHandler 

The following code example demonstrates a typical usage pattern for this event.

void Current_Activated(object sender, Windows.UI.Core.WindowActivatedEventArgs e)
{
    if (e.WindowActivationState == 
        Windows.UI.Core.CoreWindowActivationState.Deactivated)
    {
        // Show the "paused" UI. 
        VisualStateManager.GoToState(this, "PauseUI", false);
    }
    else if (e.WindowActivationState == 
        Windows.UI.Core.CoreWindowActivationState.PointerActivated)
    {
        // Show the "active" UI. 
        VisualStateManager.GoToState(this, "ActivateUI", false);
    }
}

This event occurs when a Window has been activated or deactivated by the system. An app can determine what the status of the Window activation is by checking the WindowActivatedEventArgs.WindowActivationState property. A Window could be visible on screen but not be active (for example, in snapped apps). Additionally, if any other parts of the system takes focus away from the window, this event will occur. This could happen as a result of user interaction or code, and the WindowActivationState will indicate which action has taken place.