Old Name was. "Implement a feature to change the Value property based on the Text property ". However, Value is the primary property for this control and that is why we want clients to use Value property, not two-way binding of the Text property that changes the Value internally. That is why we changed the name of the feature request.

Its meaningful and clients will benefit from it. Basically clients want the literals to be included in in the VALUE. And this is meaningful only in TextInput. So new property in RadMaskedTextInput (for ex. IncludeLiteralsInValue) seems fine - Estimate 10. 

Example Scenario: 

Mask="##--##--##", 

User types 123456, Value property becomes "12--34--56" which will have the same value as the Text property.

Example Scenario:

IP Address SDK demo. Look at its code - there is converter in file and convert methods in ViewModel.cs. Both Value and Text are bound. If Value includes the dots, only 1 converter and 1 2way bingding would do the job with less code.

Add built in masks for Email, IP, Phone, etc. Add design time support for this.

Currently, performing consecutively paste operation does not work like in TextBox. In TextBox the strings are concatenated but in MaskedTextInput the caret is in the beggining and only the first paste is successful. 

Possibility to enter numbers with non-fixed number of digits after the decimal separator.
The SDK sample DynamicFormatString demonstrates such behavior.

Here is a link to it = > https://github.com/telerik/xaml-sdk/tree/master/MaskedInput/DynamicFormatString

We are marking this feature request as Declined - we won't introduce built-in logic for it. 

Provide a way to set .5 and display it like 0.5 , not 5.0 in No-Mask Numeric input.

When you set the IsCurrencySymbolVisible to false and Mask="1.x" you are not able to fill the first digit. 
For example if you want to insert 1.234 and you press 1 the control fills 0.001 and all other digits can be added at the last position only.

Supporting DateTimeOffset for DateTime masks

When using German Culture, NoMask and FormatString = "n0" , an incorrect input is produced.

For example pressing 4 times "6" will produce a Value of 7.

This is a parsing issue (6666 becomes 6.666 where "." is a grouping symbol in German Culture).

Then 6.666 is parsed with rounding to 7.

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.

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.

Currently, performing consecutively paste operation does not work like in TextBox. 
In TextBox the strings are concatenated but in MaskedTextInput the caret is in the beggining and only the first paste is successful.

The XAML team has recently reviewed the status of this feature request and will not be addressing it in future.
Consecutive Paste operation works in No-Masked scenario (Set Mask=""). Changing the paste behavior in masked scenarios would be a breaking change for some of our clients. 

In MaskedNumericInput when Mask="p2" you can not delete/replace the minus "-" sign when you select all and type a digit.

With no-mask, select all then typing a digit will remove the negative sign symbol from the text.

As a workaround, users can use Mask="", FormatString="p0" and maskedInput:MaskedInputExtensions.Maximum="0.99".

Second Workaround:

<telerik:RadMaskedNumericInput Mask="p2" Value="-0.25" x:Name="input" PreviewKeyDown="MaskedInput_PreviewKeyDown"/>

        private void MaskedInput_PreviewKeyDown(object sender, KeyEventArgs e)
        {
            string keyString = e.Key.ToString();
            if (keyString.StartsWith("D") && keyString.Length == 2)
            {
                if (this.input.SelectionLength == "-AA %".Length)
                {
                    this.input.ClearCommand.Execute(null);
                }
            }
        }

Edit: Actually this is default behavior for NumericIinput with default Masks #9.2. Select All on negative value then pressing digit does not remove the negative sign.
This is the reason we will mark this bug as Declined. Please use some of the mentioned workarounds.
Please submit a support ticket via our ticketing system if this feature is critical for your business requirement.

Currently the MaskedInput controls cannot handle properly Chinese input symbols from Google Pinyin or MS IME.

MaskedInput's code relies on methods from TextBox which do not fire when the input is not from keyboard.

When the user inputs digits in the RadMaskedNumericInput and then inputs some Spaces, the Value property is not changed although the UpdateValueEvent="PropertyChanged". It is only changed when the focus is lost.

Hitting dot or comma on the keyboard doesn't move the cursor after the decimal separator in the MaskedNumeric/CurrencyInput controls in Mac

Placeholder is set to " " and the SelectionOnFocus is set to CaretOnBeggining. When the Mask receives the focus, the caret is under the MouseClick position, not in beggining.
After load and clicking in the center of the MaskedInput , no value can be inserted.

The xaml team recently reviewed the status of this issue and won't be addressing it in future. 
Placeholder set to string.empty or ' ' should be considered not supported. Please consider using Mask="" (no-mask) instead.

The minus key on a Mac keyboard, doesn't toggle the sign of the values in the MaskedNumeric/CurrencyInput controls. However, if an external usb keyboard is attached to the machine, it can be used to toggle the sign as expected.

Select text in the RadMaskedTextInput then Ctrl + X cuts the text but Ctrl + V does not paste it.

Steps to reproduce:
1) Type 12345. Select 345.
2) Ctr + X.
3) Ctrl + V won't do anything. (345 is not pasted) the result is - "_______________"). 
Expected result is: "345". This  should replace the whole text with the copied one. SelectionStart is not changed after paste.

Notes:  This bug is only for the scenario Cut + Paste in the MaskedTextInput with Mask. 
Pasting in No-Masked MaskedTextInput (Mask="") should work much like pasting in normal TextBox (in the same scenario the result should be "12345"). 

Numeric input with  Mask="#7" or CurrencyInput with       Mask="c7" .

 UpdateValueEvent="LostFocus"

Value =3000

If you remove the digit "3" with backspace / delete and then type digit 4,  You will receive value"4" and text "0004".

The expected result is Text="4000" and value =4000.

Workaround:  Use Mask="" (no-mask).
=============
Fixed in R3 2016.

Japanese input symbols are not correctly displayed. Empty symbols are shown on left of the japanese symbols.
Exception occurs when entering  n japanese symbols with mask = an. For example when Mask = "a4", 4 symbols entered in MaskedTextInput. This might lead to a crash.