title: WPFToolkit Charts leak memory, any fixes or alternatives?
body: <p>I've found that the chart controls in the WPFToolkit library leak memory. I am using them in an MVVM setup, where I bind the ItemSource of the chart control (PieSeries or BarSeries) to an ObservableCollection on my ViewModel. I sometimes Clear() the ObservableCollection and then Add() new KeyValuePairs to it (when the user triggers a SelectionChanged event on a ComboBox to see a different set of data). That's how I change the data in the chart. However, the memory is not released. I've found that if I comment out the control in the XAML, the memory problem goes away, even if I still Add to the collection.</p>
  
  <p>Are there any good fixes for this memory leak? Or alternative toolkits that are free?</p>
  
  <p>Thanks!</p>