In the current version of RadNumericUpDown control it is not possible to retain the "%" symbol when the control is focused because it enters editing mode. In that mode the text displayed in the control's TextBox is used for the build-in parsing and the special symbols are removed. You can take a look at this
help article that describes the different formatting possibilities of the control.
If the desired behavior is to have a masked formatting you can take a look at our RadMaskedInput
controls which could be useful in your scenario.
TRY TELERIK'S NEWEST PRODUCT - EQATEC APPLICATION ANALYTICS for WPF.
Learn what features your users use (or don't use) in your application. Know your audience. Target it better. Develop wisely.
Sign up for Free application insights >>