To reproduce:
1.Add a RadButton and on its Click event, show a RadMessageBox.
2.Add a RadDropDownList .
3.Drag several themes from the toolbox and drop them onto the form (e.g. Office2010Black, Office2010Blue, TelerikMetro, Windows8)
4.Use the following code:

public Form1()
{
    InitializeComponent();

    this.radDropDownList1.Items.Add("Office2010Black");
    this.radDropDownList1.Items.Add("Office2010Blue");
    this.radDropDownList1.Items.Add("TelerikMetro");
    this.radDropDownList1.Items.Add("Windows8");

    this.radDropDownList1.SelectedIndexChanged += radDropDownList1_SelectedIndexChanged;
    this.radDropDownList1.SelectedItem = this.radDropDownList1.Items[0];
}

private void radDropDownList1_SelectedIndexChanged(object sender,
    Telerik.WinControls.UI.Data.PositionChangedEventArgs e)
{
    string itemText = this.radDropDownList1.Items[e.Position].Text;           
    ThemeResolutionService.ApplicationThemeName = itemText;
}

private void radButton1_Click(object sender, EventArgs e)
{
    RadMessageBox.Show("Some message", "Confirmation", MessageBoxButtons.OKCancel);
}

When you select a new item from the RadDropDownList, the theme for the entire application is changed. But when you click the button to show a RadMessageBox, the RadMessageBox has incorrect style for its buttons.

Workaround: set the RadMessageBox.ThemeName before showing it:

RadMessageBox.ThemeName = ThemeResolutionService.ApplicationThemeName;
RadMessageBox.Show("Some message", "Confirmation", MessageBoxButtons.OKCancel);

If you have a RadForm that contains a RadTextBox (TextBox), set the WindowsState of this form to Maximized and add this form to an MDI Parent with RadDock which handles the forms, you will notived that you are not able to mouse select the text.

To reproduce:
- Create blank WinForms RadForm Application.
- Set WindowState property to Maximized.
- Add RadGroupBox to the form. Set equal space on all sides.
- Anchor the group box to all sides.
- Launch application - spacing around outside of group box is incorrect.
-  Restore form to normal size - spacing around group box is incorrect.

Workaround:
radGroupBox1.Dock = DockStyle.Fill;
radGroupBox1.GroupBoxElement.Margin = new Padding(20);

To reproduce: 
1. Use the following code snippet: 
RadMessageBox.Show("RadMessageBox Some message box text", "Caption", MessageBoxButtons.OK, RadMessageIcon.Error);
2. The text is not aligned with the icon

To reproduce:
public partial class Form1 : RadForm
{
    public Form1()
    {
        InitializeComponent();
        this.IsMdiContainer = true;
    }

    private void radButton1_Click(object sender, EventArgs e)
    {
        RadForm childForm = new RadForm();
      
        childForm.Text = "MDI Child " + DateTime.Now.ToShortTimeString();
        childForm.MdiParent = this;
        childForm.WindowState = FormWindowState.Maximized;
        childForm.Show();
    }
}

QSF Forms&Dialogs Message box - show RadMessageBox when click on the right side of the title bar the popup dialog cannot be dragged.

To reproduce:

private void radButton1_Click(object sender, EventArgs e)
{
    Application.Exit();
}

private void Form1_FormClosing(object sender, FormClosingEventArgs e)
{
    RadMessageBox.Show("Do you want to exit?", "Confirmation", MessageBoxButtons.YesNo);
}


Workaround: Show the RadMessageBox first and then call the Application.Exit method according to the DialogResult.

DECLINED: 
When Application.Exit() is called it iterates through all forms and for each of them calls the FormClosing event. Currently the RadMessageBox is shown in a new form. So in this case during the iterating forms collection a new form is added and this causes the exception "Collection was modified; enumeration operation may not execute.". 
This is expected behavior and there are two possible solutions to prevent application from throwing exception: 
- Use this.Close(); to close the application.
- Make your checks, show RadMessageBox and after that, if needed call Application.Exit(); 

To reproduce:
  RadMessageBox.Instance.Font = new Font("Segoe UI", 10);
            foreach (Control c in RadMessageBox.Instance.Controls)
            {
                c.Font = new Font("Segoe UI", 14);
            }
            RadMessageBox.SetThemeName("TelerikMetro");

            RadMessageBox.Show("test", "test2", MessageBoxButtons.YesNoCancel,                  
            RadMessageIcon.Error, MessageBoxDefaultButton.Button2);

WORKAROUND: use smaller font size

To reproduce:

Create a RadForm and set the property as follows:

public Form1()
{
    InitializeComponent();
    this.FormBorderStyle = System.Windows.Forms.FormBorderStyle.FixedToolWindow;
}

Workaround:

Set the ShowIcon property to false:

public Form1()
{
    InitializeComponent();
    this.FormBorderStyle = System.Windows.Forms.FormBorderStyle.FixedToolWindow;
    this.ShowIcon = false;
}

Option to show RadMessageBox in task bar

Resolution: 

You can use the following code snippet show the message box in the taskbar: 

RadMessageBox.Instance.ShowInTaskbar = true;

To reproduce:
Add a RadRibbonBar, associate AcceptButton and CancelButton and subscribe to their events. Run the application press escape and the CancelButton's event should be fired. Press enter -  no results.
Workaround:
protected override bool ProcessCmdKey(ref System.Windows.Forms.Message msg, System.Windows.Forms.Keys keyData)
{
    if (keyData == System.Windows.Forms.Keys.Enter)
    {
        this.AcceptButton.PerformClick();
    }

    return base.ProcessCmdKey(ref msg, keyData);
}

Resolution: 

The issue is fixed in Telerik`s RadForm and RadRibbonForm. If you use MS Form, this is still not working.  

Workaround: use RadRibbonForm instead or set minimum and maximum size

To reproduce:

Show RadMessageBox as follows:

RadMessageBox.Show(this, "מסר כלשהו", "Caption", MessageBoxButtons.OKCancel, RadMessageIcon.Error, MessageBoxDefaultButton.Button1, RightToLeft.Yes, "מסר2 כלשהו");

Open the details button and you will see that the text is כלשהו מסר2

FIX. RadForm text flickers on change

To reproduce:
- Set the form MinimumSize to or close to the RadForm's actual size.
- Turn all windows visual effects off
- Set the theme to Office2010Silver
- Start the application

Workaround: 
- Load the theme manually in code like this:
 ThemeResolutionService.LoadPackageFile("C:\Office2010Silver.tssp")
 ThemeResolutionService.ApplicationThemeName = "Office2010Silver"

Steps to reproduce:
1. Add a RadPropertyGrid to a form and subscribe for the PropertyValidating event
2. In the event handler show a RadMessageBox

Run the project and change a property. Try to save the value and you will see an exception.

After each call to the Show method of RadMessageBox, the message box form is disposed. This causes each new call to Instance (or Show which internally calls Instance) to create a new instance of a message box form, loosing any user settings.

We should allow users to turn off the sound played when a RadMessageBox is shown.