To reproduce:
1. Add ribbon with a tab, group and a RadTextBoxElement.
2. Open Edit UI Elements from the smart tag, select the TextBoxItem and set the MultiLine to true 
3. Run the app and the text box is not multiline

Workaround:
set it in code:             radTextBoxElement1.TextBoxItem.Multiline = true;

If the size of the text and icons on the screen is set to larger and the font of the text is set to 12 pixels. Letters that have tails below (such as: g, j, y) are not shown properly inside the text box. 

Workaround:

As a workaround one can set the minimum height of the text box to be as the height of the text and allow multi lines.

int textHeight = TextRenderer.MeasureText(this.radTextBox1.Text, this.radTextBox1.Font).Height;this.radTextBox1.TextBoxElement.TextBoxItem.MinSize = new Size(0, textHeight);this.radTextBox1.TextBoxElement.TextBoxItem.InvalidateMeasure();this.radTextBox1.TextBoxElement.TextBoxItem.UpdateLayout();this.radTextBox1.Multiline = true;

1. Create new project and add RadTextBox inside a user control.
2. Set its Dock property to Left.
3. Add custom button items in its layout by using RadButtonElement and StackLayoutElement.
4. Set a default value to the text box when handling the form Load event.
5. Run the project.

To reproduce: 
- add a RadTextBox with empty Text property but NullText property has some value.
- change the Font style to Microsoft Sans Serif, 8.5pt. As a result the RadTextBox height is decresed a little and the NullText is cut off

Workaround: use Text property instead of NullText and cutomize its ForeColor to gray:
Font newFont = new Font("Microsoft Sans Serif", 8.5f);

public Form1()
{
    InitializeComponent();

    this.radTextBox1.Font = newFont;
    this.radTextBox1.Text = this.radTextBox1.NullText;
    this.radTextBox1.TextBoxElement.ForeColor = Color.Gray;
    this.radTextBox1.GotFocus+=radTextBox1_GotFocus;
    this.radTextBox1.LostFocus+=radTextBox1_LostFocus;

    this.radButton1.Select();
}

private void radTextBox1_LostFocus(object sender, EventArgs e)
{
   if (this.radTextBox1.Text==this.radTextBox1.NullText||this.radTextBox1.Text==string.Empty)
    {
        this.radTextBox1.Text = this.radTextBox1.NullText;
        this.radTextBox1.TextBoxElement.ForeColor = Color.Gray;
    }
    else
    {
         this.radTextBox1.TextBoxElement.ForeColor = Color.Black;
    }
}

private void radTextBox1_GotFocus(object sender, EventArgs e)
{
    if (this.radTextBox1.Text==this.radTextBox1.NullText)
    {
        this.radTextBox1.Text = string.Empty;
        this.radTextBox1.TextBoxElement.ForeColor = Color.Gray;
    }
    else
    {
         this.radTextBox1.TextBoxElement.ForeColor = Color.Black;
    }
}

To reproduce:

this.radSpellChecker1.AutoSpellCheckControl = this.radTextBoxControl1;
this.radTextBoxControl1.Text = "this is a test [doc]";

private void radButton1_Click(object sender, EventArgs e)
{
    radSpellChecker1.Check(radTextBoxControl1);
}

The "[doc]" is underlined as misspelled. However, if you click the button, no mistakes will be found.

Workaround:

char[] punctuation = " .,!?-\\/|~!@#$%^&*()[]_+=;:".ToCharArray();
TextBoxSpellChecker tbSpellChecker = this.radSpellChecker1.GetControlSpellChecker(typeof(RadTextBoxControl)) as TextBoxSpellChecker;

FieldInfo fi = typeof(TextBoxSpellChecker).GetField("punctuation",
    System.Reflection.BindingFlags.NonPublic | System.Reflection.BindingFlags.Instance);
fi.SetValue(tbSpellChecker, punctuation);

When users select the "Ignore All" on the certain word the other ocupation of this word still market as wrong.

example:

Imports Telerik.WinControls.UI
Imports Telerik.WinControls.RichTextBox.Proofing
Imports System.IO
Imports System.Globalization

Public Class Form1

    Dim radTextBox1 As RadTextBox = New RadTextBox
    Dim radSpellChecker1 As RadSpellChecker = New RadSpellChecker

    Private Sub Form1_Load(ByVal sender As Object, ByVal e As EventArgs) Handles Me.Load
        radTextBox1.Parent = Me.Panel1
        radTextBox1.Multiline = True
        radTextBox1.Dock = DockStyle.Fill

        radSpellChecker1.SpellCheckMode = SpellCheckMode.WordByWord



        Dim textBoxControlSpellChecker As IControlSpellChecker = Me.radSpellChecker1.GetControlSpellChecker(GetType(RadTextBox))
        Dim documentSpellChecker As DocumentSpellChecker = TryCast(textBoxControlSpellChecker.SpellChecker, DocumentSpellChecker)
        Dim ms As New MemoryStream(My.Resources.sv_SE
                                   )
        Dim dictionary As New WordDictionary()
        dictionary.Load(ms)

        documentSpellChecker.AddDictionary(dictionary, CultureInfo.CurrentCulture)

        radSpellChecker1.SpellCheckMode = SpellCheckMode.AllAtOnce

    End Sub

    Private Sub Button1_Click(ByVal sender As Object, ByVal e As EventArgs) Handles Button1.Click
     
        Me.radSpellChecker1.Check(Me.radTextBox1)
    End Sub
End Class

To reproduce:
- Try to set the  alignment:
radPopupEditor1.PopupEditorElement.PopupContainerForm.HorizontalPopupAlignment = HorizontalPopupAlignment.RightToRight;
radPopupEditor1.Popup.HorizontalPopupAlignment = HorizontalPopupAlignment.RightToRight;

- The property is reset when the popup is opened.

Workaround:
void radPopupEditor1_PopupOpening(object sender, CancelEventArgs e)
{
    RadPopupOpeningEventArgs args = e as RadPopupOpeningEventArgs;
    int width = radPopupContainer1.Width;

    args.CustomLocation = new Point(args.CustomLocation.X - width + radPopupEditor1.Width, args.CustomLocation.Y);
}

To reproduce:
- Set the mask to numeric.
- Change the value and check the Modified property.

- Workaround:
string oldValue = string.Empty;

void radMaskedEditBox1_LostFocus(object sender, EventArgs e)
{
    if (oldValue != radMaskedEditBox1.Text)
    {
        radMaskedEditBox1.Modified = true;
    }
    else
    {
        radMaskedEditBox1.Modified = false;
    }

    oldValue = radMaskedEditBox1.Text;
}

To reproduce:
 radMaskedEditBox1.MaskType = Telerik.WinControls.UI.MaskType.Standard;
 radMaskedEditBox1.Mask = "000-000-0000";

- Paste: 999 999 9999 when there is no selected text.

To reproduce:
- Set the mask like this:
 radMaskedEditBox1.MaskType = Telerik.WinControls.UI.MaskType.Standard;
 radMaskedEditBox1.Mask = "000-000-0000";

- Select the entire content and paste the following: 66677711111

Html formatting does not work as expected in design-time.

To reproduce:
- Drop RadMarkupDialog on the form
- In code set its DefaultFont and show it

WORKAROUND:
Create an instance of RadMarkupDialog prior showing it, not at design time.

To reproduce:
- Change the culture of the RadDateTime picker to Russian.
- Change the month to August and select the month part when the drop down is closed.

Workaround:
radDateTimePicker1.Format = DateTimePickerFormat.Custom;
radDateTimePicker1.CustomFormat = "dd/MMM/yyyy";

To reproduce:
- Set the font for all dates.
- Zoom In and out.

Workaround:
Use the ZoomChanged event and change the font while one zooms as well.

To reproduce:
public Form1()
{
    InitializeComponent();
    AddDateTime();
    radDateTimePicker1.ValueChanged += radDateTimePicker1_ValueChanged;
  
    radDateTimePicker1.Format = DateTimePickerFormat.Custom;
    radDateTimePicker1.CustomFormat = "dd/MM/yyyy HH:mm";

    AddButton();

}

void radDateTimePicker1_ValueChanged(object sender, EventArgs e)
{
    if (radDateTimePicker1.Value.Date.Hour == 0)
    {
        var date = radDateTimePicker1.Value.Date;
        radDateTimePicker1.Value = new DateTime(date.Year, date.Month, date.Day, 23, 59, 0);
    }
   
}

Workaround: 
Refocus the control and the value will be updated.

Workaround: 
((StackLayoutElement)this.radBrowseEditor1.BrowseElement.Children[2]).ShouldHandleMouseInput = false;
this.radBrowseEditor1.BrowseElement.TextBoxItem.RouteMessages = true;

When you focus a RadTextBox you will notice the keyboard button that popups next to the focused control. However, for the RadAutoCompleteBox this keyboard button does not show.

Workaround: show it manually on the GotFocus event and hide it on the LostFocus event 

private void radTextBox1_GotFocus(object sender, EventArgs e)
{
    string progFiles = @"C:\Program Files\Common Files\Microsoft Shared\ink";
    string keyboardPath = Path.Combine(progFiles, "TabTip.exe");
    Process.Start(keyboardPath);
}
 
private void radTextBox1_LostFocus(object sender, EventArgs e)
{
    var procs = Process.GetProcessesByName("TabTip");
    if (procs.Length != 0)
        procs[0].Kill();
}

Currently, when Delete is pressed the min values is set, however, the textbox should be cleared. 

This can be handled by using a custom provider:
public class MyFreeFormDateTimeProvider : FreeFormDateTimeProvider
{
    public MyFreeFormDateTimeProvider(string mask, CultureInfo culture, RadMaskedEditBoxElement owner)
        : base(mask, culture, owner)
    { }
    public override void KeyDown(object sender, KeyEventArgs e)
    {
        if (e.KeyValue != 46)
        {
            base.KeyDown(sender, e);
        }         
    }
}