<BrowsableAttribute(False)>
Public Overridable ReadOnly Property IsInteractiveModeBusy As Boolean

Dim instance As RasterImageViewer
Dim value As Boolean
 
value = instance.IsInteractiveModeBusy

[BrowsableAttribute(false)]
public virtual bool IsInteractiveModeBusy {get;}

[BrowsableAttribute(false)]
public:
virtual property bool IsInteractiveModeBusy {
   bool get();
}

Private Sub MyRasterViewerRectangleEventHandler(ByVal sender As Object, ByVal e As RasterViewerRectangleEventArgs)
   Dim viewer As RasterImageViewer = CType(IIf(TypeOf sender Is RasterImageViewer, sender, Nothing), RasterImageViewer)
   Dim ee As RasterViewerRectangleEventArgs = New RasterViewerRectangleEventArgs(e.Status, e.Rectangle)
   If ((e.Rectangle.Left > e.Rectangle.Right) OrElse (e.Rectangle.Top > e.Rectangle.Bottom)) AndAlso e.Status = RasterViewerInteractiveStatus.End Then
      e.Cancel = True
      viewer.Invalidate()
      If (Not viewer.IsInteractiveModeBusy) Then
         MessageBox.Show("Interactive mode (Rectangular region) cancelled")
         viewer.InteractiveMode = RasterViewerInteractiveMode.None
      End If
   End If
   Console.WriteLine("" & e.Rectangle.Left & ", " & e.Rectangle.Top & ", " & e.Rectangle.Right & ", " & e.Rectangle.Bottom)
End Sub

Public Sub RasterImageViewer_IsInteractiveModeBusy(ByVal viewer As RasterImageViewer)
   AddHandler viewer.InteractiveRegionRectangle, AddressOf MyRasterViewerRectangleEventHandler
   viewer.InteractiveMode = RasterViewerInteractiveMode.Region
   viewer.InteractiveRegionType = RasterViewerInteractiveRegionType.Rectangle

   MessageBox.Show("Interactive mode set to draw a rectangular region." & Constants.vbLf & "If mouse is dragged up or to the left, interactive mode is cancelled")
End Sub

private void MyRasterViewerRectangleEventHandler(object sender, RasterViewerRectangleEventArgs e)
{
   RasterImageViewer viewer = sender as RasterImageViewer;
  RasterViewerRectangleEventArgs ee = new RasterViewerRectangleEventArgs(e.Status, e.Rectangle);
  if (((e.Rectangle.Left > e.Rectangle.Right) || (e.Rectangle.Top > e.Rectangle.Bottom)) && e.Status == RasterViewerInteractiveStatus.End)
  {
     e.Cancel = true;
     viewer.Invalidate();
     if(!viewer.IsInteractiveModeBusy)
     {
        MessageBox.Show("Interactive mode (Rectangular region) cancelled");
        viewer.InteractiveMode = RasterViewerInteractiveMode.None;
     }
  }
  Console.WriteLine(@"" + e.Rectangle.Left + ", " + e.Rectangle.Top + ", " + e.Rectangle.Right + ", " + e.Rectangle.Bottom);
}

public void RasterImageViewer_IsInteractiveModeBusy(RasterImageViewer viewer)
{
   viewer.InteractiveRegionRectangle += new EventHandler<RasterViewerRectangleEventArgs>(MyRasterViewerRectangleEventHandler);
   viewer.InteractiveMode = RasterViewerInteractiveMode.Region;
   viewer.InteractiveRegionType = RasterViewerInteractiveRegionType.Rectangle;

   MessageBox.Show("Interactive mode set to draw a rectangular region.\nIf mouse is dragged up or to the left, interactive mode is cancelled");
}