title: Changing FlowDirection of a cell in Wpf's DataGrid
body: <p>I Have a DataGrid with its FlowDirection set to "RightToLeft". Problem is when displaying negative numbers, the minus sign is shown on the opposite side. 
  Setting the FlowDirection of the cell itself to "LeftToRight" fixes it, but then the left border of the cell moves to the right, so I have no border on the left, and a double border on the right.
  How can I fix this?</p>