title: XCeed WPF DataGrid: FilterCell for a specific property of converted value
body: <p>I am using <strong>XCeed DataGrid for WPF v4.0</strong>. 
  My data grid control has got one column with <code>FieldName=PropA</code>. Using <code>DisplayMemberBindingInfo</code> I convert its value to another class object with two properties in it <strong><em>1. Content 2. BackGroundColor</em></strong>. Inside <code>CellContentTemplate</code> I use property <strong>Content</strong> as cell content and property <strong>BackGroundColor</strong> as background color of that cell. I am not able to understand how should I create FilterCell for this column so that I would be able to filter rows on cell <strong>content</strong>. Does <code>Converted Class</code> need to implement any interface for this? </p>
  
  <p><img src="https://i.stack.imgur.com/pNGw1.png" alt="enter image description here"></p>