<syncfusion:DoubleTextBox NumberGroupSeparator=" " NumberDecimalDigits="2" NumberDecimalSeparator="," TextWrapping="Wrap" Text="DoubleTextBox" />
In this example with "DoubleTextBox" the keys "," and "." entry are accepted as decimal separator.
<syncfusion:CurrencyTextBox Value="0" TextAlignment="Right" CurrencyDecimalSeparator="," CurrencyDecimalDigits="2" CurrencyGroupSeparator=" " CurrencySymbolPosition="Right" NullValue="0"/>
In this example with "CurrencyTextBox" keys only, "," is accepted as decimal separator entry.
I would accept the keys "," and "." as decimal separator and having to display "," as decimal separator.