title: ComboBox in a DataGrid Cell in WPF MVVM
body: <p>I am working on a WPF MVVM Project.</p>
  
  <p>Now i have a DataGrid in which i want this.</p>
  
  <p>When ever the user comes to the FirstColumn of the DataGrid the Cell should be transformed into ComboBox and when user goes out of that cell the ComboBox should disappear and ComboBox selected value to the CellText.</p>
  
  <p>How can i do that.</p>
  
  <p>Only the selected Cell in the first column should have ComboBox</p>