The size of RadForm under Windows XP is incorrect when its initial state as MDI child is Maximized and after that the state is changed to Normal.

Workaround:
Imports Telerik.WinControls.UI

Public Class BaseRadForm
    Inherits RadForm 

    Private Shared LastWindowState As FormWindowState = FormWindowState.Normal
    Private Shared suspendClientSizeChangedFlag As Boolean = False
 
    Protected Overrides Sub OnResizeBegin(ByVal e As System.EventArgs)
        Me.MaximumSize = New Size(0, 0)
        MyBase.OnResizeBegin(e) 
    End Sub
     
    Protected Overrides Sub OnActivated(ByVal e As System.EventArgs)
        Me.MaximumSize = New Size(0, 0)
        MyBase.OnActivated(e)
    End Sub

    Protected Overrides Sub OnDeactivate(ByVal e As System.EventArgs)
        Me.MaximumSize = New Size(0, 0)
        MyBase.OnDeactivate(e)
    End Sub

    Protected Overrides Sub OnClientSizeChanged(ByVal e As System.EventArgs)
        Dim osInfo As System.OperatingSystem = System.Environment.OSVersion
        If (suspendClientSizeChangedFlag OrElse osInfo.Version.Major >= 6) Then
            Return
        End If

        If Not LastWindowState.Equals(Me.WindowState) Then
            LastWindowState = Me.WindowState
            If Me.WindowState.Equals(FormWindowState.Normal) Then
                suspendClientSizeChangedFlag = True
                Me.MaximumSize = New Size(500, 500)
                suspendClientSizeChangedFlag = False
            ElseIf Me.WindowState.Equals(FormWindowState.Maximized) Then
                Me.MaximumSize = New Size(0, 0)
            End If
        Else
            Me.MaximumSize = New Size(0, 0)
        End If

        MyBase.OnClientSizeChanged(e)

    End Sub


End Class

FIX. RadForm text flickers on change

RadRibbonForm is flickering, when it is used as MDI Parent with applied background image.

With the following property settings RadForm does not maximize in order to overlap the taskbar:
TopMost - true
WindowState = Maximized
FormBorderStyle = None

When the RadForm is used as MDI Child hosted by RadDock, the rendering of the form is not appropriate.

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.

When you set the FormBorderStyle property to FormBorderStyle.None, the form size defined initially is changed.

Default button focus is not correct and additional tab press is needed.

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;

There should be an option to show a help button at the titlebar part of RadForm

RadForm loses its scrollbars when maximized and also throws an exception in rare cases when the user scrolls with the mouse wheel.

When HTML-formatted text is displayed in RadMessageBox, it is cut off on the right.

When a user double-clicks the OK button at design-time, an empty event handler is created.
However, this handler needs the WithEvents keyword in the Designer of the form.