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;

How to reproduce: also check the attached video
this.radMaskedEditBox1.MaskType = MaskType.Numeric;

Workaround:
private void RadMaskedEditBox1_TextChanged(object sender, EventArgs e)
{
    if (this.radMaskedEditBox1.Text == "-0")
    {
        if (this.radMaskedEditBox1.MaskedEditBoxElement.TextBoxItem.Text.Length == 2)
        {
            //Workaround
            this.radMaskedEditBox1.MaskedEditBoxElement.TextBoxItem.Text = this.radMaskedEditBox1.MaskedEditBoxElement.TextBoxItem.Text.Remove(1, 1);
        }
    }
}

Multiply line text is not correct align at the left side when control runs on Win xp.

Steps to reproduce:
this.radTextBoxControl1.Text = "This\nis a\ntest";

The workaround in the following MSDN resources results in an incorrect behavior in the header of RadDateTimePicker: https://code.msdn.microsoft.com/Fixing-Persian-Locale-for-6e66e044#content

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

All controls (i.e. RadGridView, RadPropertyGrid, etc.), which use textbox editor, containing HostedTextBoxBase descendant, can be spelled by the RadSpellChecker. But the red underline is not displayed entirely. The inside hosted text box should have a bigger height.

To reproduce use the following code and zoom to Years level:
this.radDateTimePicker1.Culture = new System.Globalization.CultureInfo("ps-AF");
radDateTimePicker1.DateTimePickerElement.Calendar.HeaderNavigationMode = Telerik.WinControls.UI.HeaderNavigationMode.Zoom;

Workaround: override the ProcessCmdKey method of the form and activate the desired control:
 protected override bool ProcessCmdKey(ref Message msg, Keys keyData)
        {
            if (keyData== Keys.Tab)
            {
                this.ActiveControl = this.radPopupEditor2.PopupEditorElement.TextBoxElement.TextBoxItem.HostedControl;
                return true;
            }
            return base.ProcessCmdKey(ref msg, keyData);
        }

IMPORTANT!!! Tab key should navigate to the next control even if the popup is opened.

To reproduce:
- Use the following format:
radDateTimePicker1.Format = DateTimePickerFormat.Custom;
radDateTimePicker1.CustomFormat = "MM/dd/yyyy";

- Clear the date and try to enter 01/01/2017 (see attched video) 

Workaround:
 radDateTimePicker1.NullDate = DateTime.MinValue.AddYears(1);

To reproduce:
this.radTextBoxControl1.Text = "dog and blue glue";
this.radTextBoxControl1.Size = new Size(50, 65);
this.radTextBoxControl1.Multiline = true;

Workaround:
use RadTextBox.

Please refer to the attached sample project and attached gif file which illustrates the desired behavior when RadForm1 is run. If you run RadForm2 which uses RadDropDownList, the binding doesn't work as expected.

Workaround:
this.radDropDownList1.SelectedIndexChanged += RadDropDownList1_SelectedIndexChanged;
this.radDropDownList1.DisplayMember = "Naziv";
this.radDropDownList1.ValueMember = "Id";
this.radDropDownList1.DataSource = bs;

private void RadDropDownList1_SelectedIndexChanged(object sender, 
    Telerik.WinControls.UI.Data.PositionChangedEventArgs e)
{
    if (e.Position > -1)
    {
        Roditelj parent = this.radDropDownList1.SelectedItem.DataBoundItem as Roditelj;
        this.radDropDownList2.DataSource = null;
        this.radDropDownList2.DisplayMember = "Naziv";
        this.radDropDownList2.ValueMember = "Id";
        this.radDropDownList2.DataSource = parent.Djeca;
    } 
}

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.

Please refer to the attached sample project and try to open the form's designer. If you comment  [DesignerSerializationVisibility(DesignerSerializationVisibility.Content)] for the EditarTextBox property (typeof(RadTextBox)), clean and rebuild, the designer is opened as expected.

Workaround: use RadTextBoxControl.

To reproduce: use the following code snippet  and try to input some numeric value

public RadForm1()
 {
     InitializeComponent(); 
     this.radMaskedEditBox1.MaskType = Telerik.WinControls.UI.MaskType.Numeric; 
     this.radMaskedEditBox1.ValueChanged += radMaskedEditBox1_ValueChanged;
 }

 private void radMaskedEditBox1_ValueChanged(object sender, EventArgs e)
 {
     Console.WriteLine(this.radMaskedEditBox1.Value);
 }

To reproduce:
radMaskedEditBox1.MaskType = MaskType.Numeric;
radMaskedEditBox1.Mask = "G";

Then enter 123.45

Workaround:
Use "N" mask with fixed decimal places.

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:

this.radDateTimePicker1.ThemeName = "TelerikMetroTouch";
var calendar1 = (radDateTimePicker1.DateTimePickerElement.CurrentBehavior as RadDateTimePickerCalendar);
calendar1.ShowTimePicker = true;

Workaround:

calendar1.Calendar.Width = 250;
calendar1.DropDownMinSize = new System.Drawing.Size(500, 250);

Please refer to the attached screenshot.

Workaround: Me.RadDateTimePicker1.DateTimePickerElement.TextBoxElement.MaxSize = New Size(0, 20)

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;
}

Use the following code snippet:

            this.radMaskedEditBox1.Mask = "99/99/99/99/99/99";
            this.radMaskedEditBox1.MaskType = Telerik.WinControls.UI.MaskType.Standard;
            this.radMaskedEditBox1.PromptChar = ' ';
            ((StandartMaskTextBoxProvider)this.radMaskedEditBox1.MaskedEditBoxElement.Provider).TryGetStandardProvider().InsertKeyMode = InsertKeyMode.Overwrite;

When the cursor is just before the last "/", if you enter a number, then the cursor does not move after this last "/". Then entering another digit overwrites the last digit typed.