Having a Value of type 550.123, then selecting "55" and changing it to 7 produces 7.123 instead of 70.123.

Possible workaround is using no-mask (Mask="") and FormatString.

You can subscribe to the PreviewKeyDown event of the control. In the event handler, you can double check if all the text is select and if the delete key is pressed. If yes, you can execute the clear command of the control.

private void TxtPhone_PreviewKeyDown(object sender, KeyEventArgs e)
        {
            var myMask = sender as RadMaskedTextInput;
            if (e.Key == Key.Delete && myMask.Text.Length == myMask.SelectionLength)
            {
                myMask.ClearCommand.Execute(null);
            }
        }

MaskedInput's Value is bound to property of an Entity class. This property has EditableAttribute.

MaskedInput's will set IsReadOnly True if the EditableAttribute's AllowEdit is False.

Clients need mechanism to stop this validation in MaskedInput.

The issue is reproducible with NoMask and UpdateValueEvent=LostFocus. The Clear button clears the whole content while deleting with the Backspace and Delete keys leaves the separator symbols. When the focus is moved outside of the masked input, the symbols are removed.

If a user has selected all text in a numeric masked input control with a decimal (eg. 12.34), if they start typing a new value with a period (eg user types .89), the integer potion of the decimal does not change (so the input control now displays 12.89 instead of 0.89). Please provide a way to clear out what's to the left of the decimal when users type the period, as this is much more inline with the expected behavior of pretty much any other input control. 

The user has selected all the text and started typing. There's no excuse for not clearing out all the text in the input control in this scenario. Our clients are rightfully frustrated with this behavior.

The MaskedTextInput Value is bound to a property whose value is modified in its setter.
 In this case the Value of the control isn't updated to the modified value of the business property.
Also if Binding Converter changes the Value, it is not updated too.
Other maskedInput controls - Numeric, Currency work in such scenarios.

Currrently the default ContextMenu of the TextBox inside the MaskedInput is used. You have to set it to null in code behind and the create custom ContextMenu in XAML / Code behind to use it successsfully.

In MaskedTextInput, users need to enter from right to left just like in NumericInput and CurrencyInput.

Allow entering an input in (exponent) scientific notation form for the RadMaskedNumericInput control

Users sometimes need to invoke Undo / Redo. Public command properties would be a possible way to go.

Currently the MaskedInput controls cannot parse strings containing such full-width symbols.

Actually the .net framework also cannot directly parse such symbols.

Currently users are not allowed to completely remove or customize the Undo/Redo actions in the RadMaskedInput controls. Consider adding extensibility points such as commands or events.

Initially, when the value is 0, the mask control could look like - $__,___.00 instead of $__,___0.00.

Currently this property works only in MaskedTextInput.

We have MaskedTextInput with InputBehavior set to Replace.

When we select part of the value or the whole value and then insert a symbol, only the first selected symbol is replaced but not the whole selected text.

Supporting DateTimeOffset for DateTime masks

The MaskedNumericInput control doesn't escape formatting characters like 'c' or 'n'.
=============
This is not reproducible in R3 2016 version.

When the Value of the RadMaskedInput (all RadMaskedInput controls) is changed in code behind, the ValueChanged event isn't fired.

SelectAll then Shift + Del makes the need of twice (Ctrl + Z) for successful undo operation.

The Mask property of the RadMaskedDateTimeInput cannot be set or changed via binding. Internally it is always set to "d".