Hello. I have the problem with stretch. I have the user control with Diagram object. And all alignment properties are Stretch. But when I ZoomOut diagram it doesn't stay stretched. I looks like it's alignment properies are Center, Center. I can't understand why? Can I send you the sample project for take and advice or I need to post code their. Initializing of the user control are in the xaml and in the code. That's why it may be too large...

Yes. For this purpose I use the following code:

	  private void OnRuler_SizeChanged(object sender, SizeChangedEventArgs e)
	  {
		if (m_Diagram.Bounds.Width < e.NewSize.Width)
		{
		    Rect newBounds = new Rect(m_Diagram.Bounds.X, m_Diagram.Bounds.Y,
			  e.NewSize.Width, m_Diagram.Bounds.Height);
		    m_Diagram.Bounds = newBounds;
		}
	  }
 

But I have the ZoomIn and ZoomOut buttons on the toolbar. And when I press ZoomOut the diagram area decreases but the ruler size is constant... An I need to fill all area by the diagram

But Diagram.ZoomFactorChanged doens't have the NewSize property in the event arguments...
I wrote the following:

	  private void OnDiagram_ZoomFactorChanged(object sender, EventArgs e)
	  {
		Rect newBounds = new Rect(m_Diagram.Bounds.X, m_Diagram.Bounds.Y,
		    m_Diagram.Bounds.Width * 100 / m_Diagram.ZoomFactor,
		    m_Diagram.Bounds.Height * 100 / m_Diagram.ZoomFactor);
		m_Diagram.Bounds = newBounds;
	  }
 

In the first look it works

Is it correct?

	  private void OnDiagram_ZoomFactorChanged(object sender, EventArgs e)
	  {
		   Rect newBounds = new Rect(m_Diagram.Bounds.X, m_Diagram.Bounds.Y,
		    m_Ruler.ActualWidth * 100 / m_Diagram.ZoomFactor,
		    m_Ruler.ActualHeight * 100 / m_Diagram.ZoomFactor);
		m_Diagram.Bounds = newBounds;
#if false
		Rect newBounds = new Rect(m_Diagram.Bounds.X, m_Diagram.Bounds.Y,
		    m_Diagram.Bounds.Width * 100 / m_Diagram.ZoomFactor,
		    m_Diagram.Bounds.Height * 100 / m_Diagram.ZoomFactor);
		m_Diagram.Bounds = newBounds;
#endif
	  }