Threading

public class SimpleButton: ESRI.ArcGISExplorer.Application.Button
{
    // References to the MapDisplay and BackgroundWorker are created, 
    // and therefore only used, on the UI thread.
    MapDisplay _md;
    BackgroundWorker _bgWorker;
    // Constructor is called on the UI thread.
    public SimpleButton()
    {
        _md = Application.ActiveMapDisplay;

        // Create an Explorer BackgroundWorker component and hook 
        // up the DoWork event handler.
        _bgWorker = new BackgroundWorker();
        _bgWorker.DoWork += new DoWorkEventHandler(DoWork);
    }
    // OnClick is called on the UI thread.
    public override void OnClick()
    {
        // Access the active display and track a Point.
        Point ptOnUIThread = _md.TrackPoint();
        if (!_bgWorker.IsBusy)
        {
            // Trigger the DoWork event handler.
            _bgWorker.RunWorkerAsync(ptOnUIThread.ToXmlString());
        }
    }
    // DoWork is called on a worker thread.
    private void DoWork(object sender,
                        ESRI.ArcGISExplorer.Threading.DoWorkEventArgs args)
    {
        Point ptOnBgThread = Point.CreateFromXmlString((string)args.Argument);

        // Perform some work on the background thread, such as
        // saving the clicked locations to a file.
        string filename = System.IO.Path.GetTempFileName();
        System.IO.StreamWriter sw = System.IO.File.CreateText(filename);
        sw.Write(ptOnBgThread.ToString());
        sw.Close();
    }
}

Public Class SimpleButton
    Inherits ESRI.ArcGISExplorer.Application.Button
    ' References to the MapDisplay and BackgroundWorker are created,
    ' and therefore only used, on the UI thread.
    Private _md As MapDisplay
    Private _bgWorker As ESRI.ArcGISExplorer.Threading.BackgroundWorker
    ' Constructor is called on the UI thread.

    Public Sub New()
        _md = ESRI.ArcGISExplorer.Application.Application.ActiveMapDisplay
        ' Create an Explorer BackgroundWorker component and hook
        ' up the DoWork event handler.
        _bgWorker = New ESRI.ArcGISExplorer.Threading.BackgroundWorker()
        AddHandler _bgWorker.DoWork, AddressOf DoWork
    End Sub

    ' OnClick is called on the UI thread.
    Public Overrides Sub OnClick()
    ' Access the active display and track a Point.
    Dim ptOnUIThread As ESRI.ArcGISExplorer.Geometry.Point = _md.TrackPoint()
    If (Not _bgWorker.IsBusy) Then
        ' Trigger the DoWork event handler.
        _bgWorker.RunWorkerAsync(ptOnUIThread.ToXmlString())
    End If
End Sub

' DoWork is called on a worker thread.

Private Sub DoWork(ByVal sender As Object, ByVal args As ESRI.ArcGISExplorer.Threading.DoWorkEventArgs)
    Dim ptOnBgThread As ESRI.ArcGISExplorer.Geometry.Point = ESRI.ArcGISExplorer.Geometry.Point.CreateFromXmlString(CStr(args.Argument))
    ' Perform some work on the background thread, such as
    ' saving the clicked locations to a file.
    Dim filename As String = System.IO.Path.GetTempFileName()
    Dim sw As System.IO.StreamWriter = System.IO.File.CreateText(filename)
    sw.Write(ptOnBgThread.ToString())
    sw.Close()
End Sub

End Class

// To serialize the selected MapItem, first get the object, then use the 
// ToXmlString helper method. This code assumes a MapItem is selected.
string selectedItemXml = Application.SelectedItems[0].ToXmlString();
// To deserialize, use CreateFromXmlString.
MapItem newItem = MapItem.CreateFromXmlString(selectedItemXml);

' To serialize the selected MapItem, first get the object, then use the
' ToXmlString helper method. This code assumes a MapItem is selected.
Dim selectedItemXml As String = ESRI.ArcGISExplorer.Application.Application.SelectedItems(0).ToXmlString()
' To deserialize, use CreateFromXmlString.
Dim newItem As MapItem = MapItem.CreateFromXmlString(selectedItemXml)