Use attached to reproduce.

1 - In the First Text Box (the Masked Box) type 1
2 -  Click the "GO" button. The text box shows 1 and the VALUE is displayed from the Edit box correctly as 1
3 - Select the 1 in the edit box and CTRL + DELETE to clear the field
4 - Click the "GO" button. The text box shows NULL and the VALUE is displayed from the Edit box correctly as NULL
5 - Highlight the text in the "Paste Me!" text box and Copy the text to Clipboard.
6 - Paste the clipboard into the Masked t Edit box
7 - Click "GO". The mask text box correctly displayed NULL however the returned VALUE is 1

 

To reproduce:

ThemeResolutionService.ApplicationThemeName = "Office2013Light";
this.radTextBox2.Enabled = false;
 
Workaround:             this.radTextBox2.BackColor = Color.LightGray;

After binding a boolean property to RadDateTimePicker:Checked, changes made in the property reflect in the GUI, but changes made in the GUI even after lost focus are not reflected on the boolean property. The same test was done with winforms DateTimePicker and the expected behaviour was observed(not the situation reported). above). For further testing background, the class wich contains the binded boolean, implements INotifyPropertyChanged.

To reproduce:

Add the following code:
int count = 0;
private void dateTimePicker1_ValueChanging(object sender, Telerik.WinControls.UI.ValueChangingEventArgs e)
{
   
    if (count == 2)
    {
        e.Cancel = true;
    }
    count++;
}

- Select the year and press down multiple times. After some time the event is not fired any more. 

Workaround:
class MyMaskDateTimeRpovider : MaskDateTimeProvider
{
    public MyMaskDateTimeRpovider(string mask, CultureInfo culture, RadMaskedEditBoxElement owner) : base(mask, culture, owner)
    { }
    public override object Value
    {
        get { return base.Value; }
        set
        {
            typeof(MaskDateTimeProvider).GetField("oldValue", BindingFlags.Instance | BindingFlags.NonPublic).SetValue(this, null);
            base.Value = value;
        }
    }

}

To reproduce:
- Use the SpellCheck as you type functionality with RadTextBox.
- The "Ignore All" and "Add To Dictionary" strings in the context menu are not changed.

Workaround:
public RadForm1()
{
    InitializeComponent();
    radSpellChecker1.AutoSpellCheckControl = radTextBox1;
    TextBoxSpellChecker textBoxControlSpellChecker = this.radSpellChecker1.GetControlSpellChecker(typeof(RadTextBox)) as TextBoxSpellChecker;
    textBoxControlSpellChecker.DropDownMenu.DropDownOpened += DropDownMenu_DropDownOpened;
}

private void DropDownMenu_DropDownOpened(object sender, EventArgs e)
{
    var menu = (RadDropDownMenu)sender;

    foreach (var item in menu.Items)
    {
        if (item.Text == "Add To Dictionary")
        {
            item.Text = "test";
        }
        if (item.Text == "Ignore All")
        {
            item.Text = "test";
        }
    }
}

To reproduce:
- Use the Fluent theme with RadSpinEditor on a HDPI monitor.

Workaround:
 var borderPrimitive = radSpinEditor1.SpinElement.Children[1] as BorderPrimitive;
borderPrimitive.BottomWidth = 2;

To reproduce:

1. Add a RadForm and a RadTimePicker/RadDateTimePicker.
2. Change the Enabled property of the RadTimePicker/RadDateTimePicker to false at design time.
3. Apply the Office2013Light theme to the RadTimePicker/RadDateTimePicker at design time.
4. Apply the same theme to the RadForm at design time.

If you run the application, you will notice that RadTimePicker/RadDateTimePicker has a gray back color. However, if you turn on/off the Enabled property in a button's Click event, the back color is not gray.

Workaround: set the Enabled property to false in the Load event.

Windows TextBox - OSK perfect

Telerik RadTextBox - OSK perfect

Telerik RadTextBoxControl - OSK doesn't work

Telerik RadDropDownList - OSK doesn't work

Telerik AutoCompleteBox - OSK doesn't work

This should work for all controls that have text input.

See attached video to reproduce.

To reproduce:
- Set the DropDownSizingMode to None
- Show the popup several times.
- Each time the height is increased.

Workaround:
var popup = radPopupEditor1.PopupEditorElement.PopupForm as RadPopupContainerForm;
popup.SizingGrip.MinSize = new Size(0, 0);

How to reproduce:  The spell checker`s AutoSpellCheckControl property must not be set. Add a ContextMenuStrip with several items and use it with a standard text box. Then perform a spell check with the RadSpellChecker control, e.g. like this: 

Me.RadSpellChecker1.Check(Me.TextBox1)

Then right-click in the text box, the context menu will not be shown.

Workaround: use RadContextMenu
https://docs.telerik.com/devtools/winforms/menus/contextmenu/context-menus

The issue exist in the versions after Q1 2017

Workaround:
Class MyTextBox
    Inherits RadTextBoxControl

    Protected Overrides Function CreateTextBoxElement() As RadTextBoxControlElement
        Return New MyTextBoxElement()

    End Function
End Class

Class MyTextBoxElement
    Inherits RadTextBoxControlElement
    Protected Overrides ReadOnly Property ThemeEffectiveType As Type
        Get
            Return GetType(RadTextBoxControlElement)

        End Get
    End Property
    Protected Overrides Function CreateViewElement() As TextBoxViewElement
        Return New MyWrapPanel

    End Function
End Class

Class MyWrapPanel
    Inherits TextBoxViewElement

    Protected Overrides Function InsertTextBlocks(index As Integer, text As String, blockType As Type) As Integer

        If String.IsNullOrEmpty(text) Then
            Return index
        End If

        Dim textBuilder As New StringBuilder()

        For i As Integer = 0 To text.Length - 1
            Dim symbol As Char = text(i)

            If Char.IsWhiteSpace(symbol) OrElse symbol = TextBoxViewElement.TabSymbol OrElse symbol = TextBoxViewElement.LineFeedSymbol OrElse symbol = TextBoxViewElement.CarriageReturnSymbol Then
                If textBuilder.Length > 0 Then
                    Dim textBlock As ITextBlock = Me.CreateBlock(textBuilder.ToString(), blockType)
                    If index >= Me.Children.Count Then
                        Me.Children.Add(TryCast(textBlock, RadElement))
                        index = Me.Children.Count - 1
                        textBlock.Index = index
                    Else
                        textBlock.Index = index
                        Me.Children.Insert(index, TryCast(textBlock, RadElement))
                    End If

                    textBuilder = New StringBuilder()

                    index += 1
                End If

                Dim tabBlock As ITextBlock = Me.CreateBlock(symbol.ToString(), blockType)
                tabBlock.Index = index
                Me.Children.Insert(index, TryCast(tabBlock, RadElement))
                index += 1
                Continue For
            End If

            textBuilder.Append(symbol)
        Next

        If textBuilder.Length > 0 Then
            Dim textBlock As ITextBlock = Me.CreateBlock(textBuilder.ToString(), blockType)
            textBlock.Index = index
            Me.Children.Insert(index, TryCast(textBlock, RadElement))
            index += 1
        End If

        Return index - 1
    End Function
End Class

Use the following code:
public RadForm1()
{
    InitializeComponent();
    radMaskedEditBox1.MaskType = Telerik.WinControls.UI.MaskType.Numeric;
    radMaskedEditBox1.Mask = "d0";
    radMaskedEditBox1.EnableNullValueInput = true;

    radMaskedEditBox1.TextChanged += RadMaskedEditBox1_TextChanged;
    radMaskedEditBox1.ValueChanged += RadMaskedEditBox1_ValueChanged;

    radMaskedEditBox1.Value = null;

}

private void RadMaskedEditBox1_ValueChanged(object sender, EventArgs e)
{
    Console.WriteLine(radMaskedEditBox1.Value);
}

- Type "1", you will notice that the value is still null.
- Type "2", the value is now correct.

Workaround:
private void RadMaskedEditBox1_ValueChanged(object sender, EventArgs e)
{
    if (radMaskedEditBox1.Text != "" )
    {
        var provider = radMaskedEditBox1.MaskedEditBoxElement.Provider;
        Console.WriteLine(provider.Value);
    }
    else
    {
        Console.WriteLine(radMaskedEditBox1.Value);
    }
  
}
er.Value);

Use attached to reproduce.

Workaround:
RadTextBox tb = new RadTextBox();

tb.Font = new Font(Font.Name, 12F, FontStyle.Bold);

tb.MaxLength = 200;
tb.Name = "textBox1";
tb.Text = "<Required>";
tb.Location = new Point(49, 7);
var pixels = tb.Font.SizeInPoints * 96 / 72;
tb.TextBoxElement.TextBoxItem.HostedControl.MinimumSize = new Size(0, (int)pixels + 6);

To reproduce:
- Open the attached project.
- Click the day part and press N
- Click the hour part and press N - PM is changed to AM

Workaround:
public RadForm1()
{
    InitializeComponent();
    radDateTimePicker1.Format = DateTimePickerFormat.Custom;
    radDateTimePicker1.CustomFormat = @"yyyy/MM/dd hh:mm:ss tt";
    radDateTimePicker1.DateTimePickerElement.TextBoxElement.TextBoxItem.KeyPress += TextBoxItem_KeyPress;
}
 
private void TextBoxItem_KeyPress(object sender, KeyPressEventArgs e)
{
    if (e.KeyChar == 'n')
    {
        e.Handled = true;
        radDateTimePicker1.Value = DateTime.Now;
    }
}

To reproduce: run the attached project, enter some text in the upper RichTextBox and use the buttons to style parts of the text. Click the Save button and you will notice that after correcting the words, the style is not preserved.

Workaround: use RadRichTextEditor which has a built-in spell checking functionality: http://docs.telerik.com/devtools/winforms/richtexteditor/features/spellcheck

We should also add padding to the RadTimePicker

Workaround: 
this.radSpinEditor1.SpinElement.Padding = new Padding(2, 0, 0, 0);
this.radTimePicker1.TimePickerElement.Padding = new Padding(2, 0, 0, 0);

To reproduce:
- Open the demo application.
- Open the PropertyGrid -> FirstLook example.
- Open the color dialog editor multiple times. 

 

To reproduce:
this.radDateTimePicker1.DateTimePickerElement.TextBoxElement.MaskType = MaskType.FreeFormDateTime;

And try pasting a date, or some free text.