Ok. I've found the solution. It works a little wrong, but it's ok. If you want to have shared X axis, you have to do next:
// Add handler
SpeedChart.Viewport.PropertyChanged += new EventHandler<ExtendedPropertyChangedEventArgs>(Viewport_PropertyChanged);
// Respond to changes
void Viewport_PropertyChanged(object sender, ExtendedPropertyChangedEventArgs e)
{
if (e.PropertyName == "Visible")
{
StrokeChart.Viewport.Visible = new DataRect(SpeedChart.Viewport.Visible.XMin, StrokeChart.Viewport.Visible.YMin, SpeedChart.Viewport.Visible.Width, StrokeChart.Viewport.Visible.Height);
}
}
Next you have to remove MouseNavigation and HorizontalAxisNavigation from StrokeChart. The problem is that the points on StrokeChart are not visible at first, because the range on Y axis is wrong. But you can zoom and drag the Y axis only for getting the proper values. If you know how to solve the problem with ranges please let me know. Thanks