Workaround: disable the default scaling and adjust the font and minimum size

        Me.RadRadioButton1.Font = New Font("Arial", 12, FontStyle.Regular)
        Me.RadRadioButton1.ButtonElement.CheckMarkPrimitive.MinSize = New Size(20, 20)
        Dim radioPrimitive As RadioPrimitive = Me.RadRadioButton1.ButtonElement.CheckMarkPrimitive.FindDescendant(Of RadioPrimitive)()
        radioPrimitive.MinSize = New Size(21, 21)

    Public Class CutsomRadioButton
        Inherits RadRadioButton
        Protected Overrides Sub ScaleControl(factor As SizeF, specified As BoundsSpecified)
             
        End Sub
    End Class

RadSplitButton does not get a focus rectangle when focus by the Tab key. One should first click the action part and then the focus rectangle will appear..

The current workaround is:
public class MyRadSplitButton : RadSplitButton 
{ 
    protected override void OnEnter(EventArgs e) 
    { 
        base.OnEnter(e); 
  
        this.DropDownButtonElement.ActionButton.Focus(); 
    } 
}

To reproduce:


Add a RadButton to a form. Set an image, remove the text and set the shape of the ButtonElement to a new RoundRectShape. You will see that the image will not be painted with a shape.


Workaround:


Paint the image manually:


Image img = Image.FromFile(@"jpg.jpg");
RoundRectShape shape1 = new RoundRectShape(10);


protected override void OnLoad(EventArgs e)
{
    this.button = new RadButton();
    this.button.Parent = this;
    this.button.ButtonElement.Shape = shape1;
    this.button.Paint += button_Paint;
}


void button_Paint(object sender, PaintEventArgs e)
{
    e.Graphics.SetClip(shape1.CreatePath(new Rectangle(Point.Empty, this.button.Size)));
    e.Graphics.DrawImage(img, new Rectangle(Point.Empty, this.button.Size));
}

To reproduce:

Add a RadTextBox and a RadButton to a form. On the Leave event of RadTextBox show a RadMessageBox. Start the application. Focus the textbox and click the button. The RadMessageBox will show, click the OK button and now you will see that the button is in its 'IsDefault' state (it is a bit more obvious with the Office2010 themes) and no other controls receive mouse input unless you click on the form.

Workaround:

Set the CausesValidation property of RadButton to false.

To reproduce:
- Add 3 radio buttons to a user control.
- Set the ToggleState of the second radio button to  On.
- Show the user control in a DockWindow.
- You will notice that the first toggle button is selected.

Workaround:
Set the toggle state after the window is added to the RadDock
void radDock1_DockWindowAdded(object sender, Telerik.WinControls.UI.Docking.DockWindowEventArgs e)
{
    if (e.DockWindow.Text == "UserControl11")
    {
        UserControl1 uc1 = e.DockWindow.Controls[0] as UserControl1;
        ((RadRadioButton)uc1.Controls[1]).ToggleState = Telerik.WinControls.Enumerations.ToggleState.On;
    }
}

To reproduce:
- Add SplitButton to a ribbon bar and set its image. 
- Disable the button.

Workaround:
this.radSplitButtonElement1.UseDefaultDisabledPaint = true;

Please refer to the attached sample project and gif file. The text gets clipped sometimes when resizing the form. It may become even blurry. This problem is observed with the MS Form, but it is not reproducible with RadForm.

Workaround: use a RadForm

UPDATED: a second project is attached (00393359CheckBoxDisabledUPDATED.zip). The MissingCheckBoxesText.gif illustrates the incorrect behavior. In this case, the UseCompatibleTextRendering property is set to false.
Workaround for the second case: instead of setting the RadCheckBox.Enabled property to false, disabled the check primitive and make the text gray as follows:

private void radButton1_Click(object sender, EventArgs e)
{
    for (int i = 0; i < 30; i++)
    {
        RadCheckBox cb = new RadCheckBox();
        cb.Text = "RadCheckBox " + i;
        cb.Location = new Point(10, i * 30); 
        cb.ButtonElement.CheckMarkPrimitive .Enabled = false;
        cb.ButtonElement.TextElement.ForeColor = Color.Gray; 
        cb.ButtonElement.ShouldHandleMouseInput = false;
        cb.UseCompatibleTextRendering = false;
         
        this.Controls.Add(cb);
    }
}

Workaround:
            
            this.radDropDownButton1.DropDownButtonElement.DropDownMenu.PopupElement.AutoSize = false;   
            this.radDropDownButton1.DropDownButtonElement.DropDownMenu.PopupElement.Size = new Size(300, 300);

How to reproduce: add several menu items displaying only images to the split button and set the MaximumSize property of the drop-down menu

Workaround:
public RadForm1()
{
    InitializeComponent();

    this.radSplitButton1.DropDownButtonElement.DropDownMenu.MaximumSize = new Size(30, 0);
    RadScrollBarElement element = this.radSplitButton1.DropDownButtonElement.DropDownMenu.PopupElement.FindDescendant<RadScrollBarElement>();
    element.Visibility = Telerik.WinControls.ElementVisibility.Collapsed;
    element.RadPropertyChanging += Element_RadPropertyChanging;
}

private void Element_RadPropertyChanging(object sender, Telerik.WinControls.RadPropertyChangingEventArgs args)
{
    if (args.Property.Name == "Visibility")
    {
        args.Cancel = true;
    }
}

To reproduce:
- Add RadDropDownButton to a blank form.
- Set its anchor property to top, right and its AutoSize property to true.
- At runtime set the button text to a long string, you will notice that the button is resized to the right when it should be resized to the left.

To workaround this you can subscribe to the SizeChanged event of the button change its location depending on the new size:
Size prevSize;

public Form1()
{
    InitializeComponent();
    radDropDownButton1.AutoSize = true;

    this.Shown += Form1_Shown;
}

void Form1_Shown(object sender, EventArgs e)
{
    prevSize = radDropDownButton1.Size;

    radDropDownButton1.SizeChanged += radDropDownButton1_SizeChanged;
}

void radDropDownButton1_SizeChanged(object sender, EventArgs e)
{
    RadDropDownButton button = sender as RadDropDownButton;
    button.Location = new Point(button.Location.X - (radDropDownButton1.Size.Width - prevSize.Width), button.Location.Y);
    prevSize = button.Size;
    
}

private void radButton2_Click(object sender, EventArgs e)
{
    radDropDownButton1.Text = "Very long button text set";
}

The following themes have differences: ControlDefault, Office2010Silver, Office2013Dark, Office2013Light, TelerikMetro, TelerikMetroBlue, TelerikMetroTouch

To reproduce:

this.radSplitButton1.DropDownButtonElement.ArrowButton.Enabled = false;
this.radSplitButtonElement1.ArrowButton.Enabled = false;

Use attached video and project to reproduce.

Workaround:
Disable the animations:

 btnAdd.DropDownButtonElement.DropDownMenu.AnimationEnabled = false;
//or
ThemeResolutionService.AllowAnimations = false;