Event on Microsoft.VisualStudio.Shell.WindowPane activation/deactivation?

Hello, I like to know how I can get be informed in case Panes are activated/deactivated.

In detail, I have implemented two different editors for specific purposes. When I have opened two or more instances of them, I like to trigger specific tasks when the different VisualStudio 2012+ Panes are activated and deactivated (in which the editors are provided).

I tried following events, but non of them is called when I click on the Pane tabs:

    public partial class TcHmiEditorFrame : UserControl
    {
public TcHmiEditorFrame()
        {
            InitializeComponent();

            this.Enter += TcHmiEditorFrame_Enter;
            this.GotFocus += TcHmiEditorFrame_GotFocus;
            this.Click += TcHmiEditorFrame_Click;
            this.EnabledChanged += TcHmiEditorFrame_EnabledChanged;
            this.Validated += TcHmiEditorFrame_Validated;
        }

        void TcHmiEditorFrame_Validated(object sender, EventArgs e)
        {
            Trace.WriteLine("<Trace> web form validated");
        }

        void TcHmiEditorFrame_EnabledChanged(object sender, EventArgs e)
        {
            Trace.WriteLine("<Trace> web form enable changed");
        }

        void TcHmiEditorFrame_Click(object sender, EventArgs e)
        {
            Trace.WriteLine("<Trace> web form click");
        }

        void TcHmiEditorFrame_GotFocus(object sender, EventArgs e)
        {
            Trace.WriteLine("<Trace> web form got focus");
        }

        void TcHmiEditorFrame_Enter(object sender, EventArgs e)
        {
            Trace.WriteLine("<Trace> web form entering");
        }

        private void webFormControlHoster_VisibleChanged(object sender, EventArgs e)
        {
            Trace.WriteLine("<Trace> web form control visibility changed");
        }
}

Any suggestions?

In the example above, just "*_VisibleChanged(...)" is called when I open/close the pane.