There is a serious bug in the AJAX radgrid, when using a bound GridNumericColumn, where NumericType = "currency" to set the display format.
When the datasource has negative amounts, this will be displayed in the format "($1.22)", which is what is expected with a currency format. But, as soon as you try to edit this column, it opens the editor, and misinterprets this negative, and transforms the amount to positive. The currency format should be shown in non edit mode, but it should interpret this properly and display a number with a negative sign in edit mode. When edit has closed, the display should revert back to currency format.
This is a very serious issue with financial applications, such as those that deal with hundreds of million sof dollars in a corporate Profit And Loss, or Forecasting system.