When filtering for a negative number in a GridNumericColumn with a Numeric Type of "Currency" and AutoPostBackOnFilter="true" filter loses its negative value on Enter keypress.
Setup to reproduce:
<telerik:RadGrid ID="RadGrid1" runat="server" AllowPaging="True" Width="800px" OnNeedDataSource="RadGrid1_NeedDataSource"
AllowFilteringByColumn="true">
<MasterTableView AutoGenerateColumns="False">
<Columns>
<telerik:GridNumericColumn DataField="Price" DataType="System.Decimal"
FilterControlAltText="Filter Price column" HeaderText="Price"
SortExpression="Price" UniqueName="Price" NumericType="Currency"
AutoPostBackOnFilter="true" CurrentFilterFunction="EqualTo">
</telerik:GridNumericColumn>
</Columns>
</MasterTableView>
</telerik:RadGrid>
C#
protected void RadGrid1_NeedDataSource(object sender, GridNeedDataSourceEventArgs e)
{
(sender as RadGrid).DataSource = Enumerable.Range(1,6).Select(x=> new { Price = Math.Pow(-1, x) * (x * 0.1 + x * 0.01) });
}