Mask="" (no-mask) and FormatStyring =n3 or n4 , n5.

Value is 0.

Typing 0 then ".", then 0, then 0, then 5 produces 0.5000 but it should produce 0.0050.

Fix available in LIB Version 2016.1.404.

MaskedNumericInput with Mask = #6.3. When there is no digit grouping (you can turn it off from  the region / format settings in windows, no digit grouping means no symbol for grouping) the control produces Exception on load.

Part of the Value or the whole value is selected in no-masked NumericInput.

Pasting a copied text is not successful. For example 4 is the value and 4 is selected. Pasting "123" produces "1" but it should produce "123".

I think it would be great to have a IsMultilineAllowed property for this control, as AcceptsReturn property is only designed to ignore the return key entered by the user.

Here is my post in the forum:
http://www.telerik.com/forums/paste-multi-line-text-when-acceptsreturn-set-to-false
========
Reason for Decline: The desired request is custom logic that could be implemented by inheriting the RadMaskedInput control and overriding HandlePaste.

Mask is "a-a". Value is set to "M-M".

The MaskedTextInput control must internally coerce the Value to "MM".
Instead , MaskedTextInput'Value is "M-" which is wrong.

Other example of the same issue:
Bound Value is bbaabbaabbdd, Mask is "aa-aa-aa-aa-aa-aa"
The result is - value becomes bbbbbbddaaaa.

Workaround:
Use custom Mask Token (check help article: http://docs.telerik.com/devtools/wpf/controls/radmaskedinput/how-to/howto-create-custom-token.html)

 public class CustomToken : ITokenValidationRule
    {
        public bool IsRequired
        {
            get { return false; }
        }

        public bool IsValid(char ch)
        {
            return ValidChars.Contains(ch.ToString());
        }

        public char Token
        {
            get { return '$'; }
        }

        public TokenTypes Type
        {
            get { return TokenTypes.AlphaNumeric; }
        }

        private string myValidChars = "0123456789qwertyuioplkjhgfdsazxcvbnm";
        public string ValidChars
        {
            get { return myValidChars; }
        }
    }

    TokenLocator.AddCustomValidationRule(new CustomToken());
            InitializeComponent();

   <telerik:RadMaskedTextInput Mask="$-$"  

Pasting text in TextInput with No-Mans and UpdateValueEvent=LostFocus is not successful.

This operation clears the whole Value.

 <telerik:RadMaskedTextInput Mask="" UpdateValueEvent="LostFocus"/>

Available in LIB version: 2014.3.1305

You have the following scenario.
The UpdateValueEvent property is set to "LostFocus" and set no mask ( Mask= "").

When the input box is focused, press the minus sign key. You can see the that the minus is showing as expected. 

Then press a number and the "-" (minus) disappear. By pressing number key again the minus appears again.

A workaround: 
Setting the UpdateValueEvent property to PropertyChanged


Available in R2 2016 SP

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

Possible workaround:
You can subscribe to the PreviewTextInput event of the control and change the position of the caret if the typed char is the same as the current one.

private void RadMaskedTextInput_PreviewTextInput(object sender, TextCompositionEventArgs e)
        {
            var input = sender as RadMaskedTextInput;
            var currentPosition = input.SelectionStart;

            if (currentPosition != input.Text.Length)
            {
                var currentChar = input.Text[currentPosition];

                if (currentChar != input.Placeholder && currentChar.ToString() == e.Text)
                {
                    input.SelectionStart++;
                }
            }
        }



Available in R3 2016 Release

Fix available in LIB Version 2017.3.1009.

A possible workaround is to subscribe to the PreviewKeyDown event of the mask then check if the back key is pressed and the whole text is select and set the value to null in order to erase the text of the mask.

private void maskTextInput_KeyDown(object sender, KeyEventArgs e)
{           
	if (e.Key == Key.Back && this.maskTextInput.SelectionLength == this.maskTextInput.Text.Length)
	{
		this.maskTextInput.Value = null;                 
	}
}

The Value property of the TextInput is not correctly updated when using the On-Screen Touch keyboard when using no mask (Mask=""). We managed to reproduce the issue on Windows 8.1, 10. The behavior is different in both Windows OS. To get the Touch Keyboard you can check the following link.

Windows OS  8.1 - When you enter text and pressed backspace key- the value property is not updated the first time.

Windows OS 10 - When you enter text and pressed backspace key the value property is updated correctly. But if you HOLD THE BACKSPACE KEY the Value property ignored this behavior.

RadMaskedCurrencyInput with the following properties:

Mask="#14.2" , FormatString="#,0.##" and IsCurrencySymbolVisible= True

Pressing minus key produces ArgumentException

Message "String cannot be of zero length.\r\nParameter name: oldValue" string

  at System.String.ReplaceInternal(String oldValue, String newValue)
   at System.String.Replace(String oldValue, String newValue)
   at Telerik.Windows.Controls.RadMaskedCurrencyInput.CoerceDisplayTextOverride()
   at Telerik.Windows.Controls.RadMaskedInputBase.CoerceDisplayText()
   at Telerik.Windows.Controls.RadMaskedInputBase.OnValueInternalChanged(DependencyObject d, DependencyPropertyChangedEventArgs args)
   at System.Windows.DependencyObject.OnPropertyChanged(DependencyPropertyChangedEventArgs e)
   at System.Windows.FrameworkElement.OnPropertyChanged(DependencyPropertyChangedEventArgs e)
   at System.Windows.DependencyObject.NotifyPropertyChange(DependencyPropertyChangedEventArgs args)
   at System.Windows.DependencyObject.UpdateEffectiveValue(EntryIndex entryIndex, DependencyProperty dp, PropertyMetadata metadata, EffectiveValueEntry oldEntry, EffectiveValueEntry& newEntry, Boolean coerceWithDeferredReference, Boolean coerceWithCurrentValue, OperationType operationType)
   at System.Windows.DependencyObject.SetValueCommon(DependencyProperty dp, Object value, PropertyMetadata metadata, Boolean coerceWithDeferredReference, Boolean coerceWithCurrentValue, OperationType operationType, Boolean isInternal)
   at System.Windows.DependencyObject.SetValue(DependencyProperty dp, Object value)
   at Telerik.Windows.Controls.RadMaskedCurrencyInput.OnIsNegativeValueChanged()
   at Telerik.Windows.Controls.RadMaskedCurrencyInput.set_IsNegativeValue(Boolean value)
   at Telerik.Windows.Controls.RadMaskedCurrencyInput.ToggleNegativeSignKey()

Available in LIB version: 2016.3.1010

Mask="Pddd" should disallow letters.

However, after select all, you can type letter in the position of the first "d"

Available in LIB Version: 2016.1.125.

I think that would be nice to add "clear value key" to radmaskednumericinput, it should be Delete key as default value, and when you press Delete key while editing , valued should be set to zero, as when Clear button clicked.

Scheduled for:
The fix for this issue will be available with LIB (version 2019.1.128) scheduled for publishing on Monday, 28th January 2019.