1.download and install the telerik trial version for ui winforms for desktop latest version 2019. 219.

2.open new project with blank template.

3.create radform and set Radform1 as mdi form. And open a child page from this..

CHild page takes 4 seconds to load. Though child page has only grid view and loads only 6000 records

Use attached to reproduce.
Case 1 - the initial scaling is not correct and the showing dilog1 results in a different DPI each time. 
Case 2 - the AllowTheming property disabled the scaling - see dialog 2.

Workaround:

this.AutoScaleMode = System.Windows.Forms.AutoScaleMode.Dpi;
this.AutoScaleDimensions = new System.Drawing.SizeF(96F, 96F);

public class MyRadForm : RadForm
{
    protected override void HandleDpiChanged()
    {
        if (TelerikHelper.IsWindows10CreatorsUpdateOrHigher)
        {
            return;
        }

        base.HandleDpiChanged();
    }

}

To reproduce:
- Set the StartPosition to CenterScreen
- Show the form on a HDPI monitor

Workaround:
var form = new RadForm();

float dpiX, dpiY;
Graphics graphics = this.CreateGraphics();
dpiX = graphics.DpiX /100;
dpiY = graphics.DpiY /100;

form.StartPosition = FormStartPosition.Manual;
var monSize = Screen.FromControl(this).Bounds;
var centerX = (monSize.Width / 2) - (form.DesktopBounds.Width * dpiX / 2);
var centerY = (monSize.Height / 2) - (form.DesktopBounds.Height * dpiY/ 2);
form.Location = new Point((int)centerX,(int) centerY);
form.Show();

To reproduce: run the sample project. It ends up leaving significant blank space on the right and the bottom, whereas the normal MS Form does NOT do this and works right.

Workaround: in the Load event you can adjust the size with 10/15 px by setting the MaximumSize:

        private void Form1_Load(object sender, EventArgs e)
        {
            this.MaximumSize = new Size(this.Size.Width - 15, this.Size.Height - 10);
        }

How to reproduce: add a RadRibbonForm and set its MaximizeBox, MinimizeBox properties to false. Set the HelpButton property of the form to true and change its Icon. You will notice that the designer in Visual Studio has not updated.

Workaround: use the element hierarchy editor and manually change the visibility of the elements.

To reproduce: Create a RadForm, select a material theme from the ToolBox, and apply the theme to the Form. Set the size of the Form to anything simple like (300, 300) and then save and close out the Form. When you reopen the same Form it will grow to (304, 302).
Please refer to the attached gif file.

Workaround: set the size at run time.

To reproduce: on some Windows 10 machines the title bar's text is not rendered clearly. 

Workaround:

1. Set the RadForm.AllowTheming property to false.

2. In the form's Load event change the TextRenderingHint of the caption text primitive to AntiAliasGridFit:  

TextPrimitive tp = this.radRibbonBar2.RibbonBarElement.RibbonCaption.CaptionLayout.CaptionTextElement as TextPrimitive;
tp.TextRenderingHint = System.Drawing.Text.TextRenderingHint.AntiAliasGridFit;

To reproduce:
- Set the icon of the form.
- Set the FormBorderStyle to FixedToolWindow.
- The default icon is displayed in the taskbar.

Workaround:
public RadForm2()
{
    InitializeComponent();
    this.ShowIcon = true;
  
}
protected override void OnShown(EventArgs e)
{
    base.OnShown(e);
    this.FormElement.TitleBar.IconPrimitive.Visibility = ElementVisibility.Collapsed;
}

How to reproduce: set the Size property of the form in the designer of Visual Studio, pay attention to the serialized ClientSize value. Run the form and check the ClientSize, it has increased

Workaround: 
public partial class Form2 : RadForm
{
    public Form2()
    {
        InitializeComponent();
        Padding p = TelerikDpiHelper.ScalePadding(this.FormBehavior.ClientMargin, new SizeF(1f / this.RootElement.DpiScaleFactor.Width, 1f / this.RootElement.DpiScaleFactor.Height));
        this.MaximumSize = new Size(this.Size.Width - p.Horizontal, this.Size.Height - p.Vertical- this.FormBehavior.ClientMargin.Bottom + this.FormElement.TitleBar.Size.Height);
    }

    protected override void OnShown(EventArgs e)
    {
        base.OnShown(e);

        this.MaximumSize = new Size(0, 0);
    }
}

To reproduce:

1. Create a RadForm - Form1
2. Change its BackColor at design time
3. Create another RadForm - Form2 
4. Open it at design time. It is expected to have the BackColor coming from the parent form.

Workaround: Set the color in the form's constructor instead of at design time.

Use attached to reproduce. This was working in version 2017.1.221

Workaround:
private void Instance_LocationChanged(object sender, EventArgs e)
{
    var box = sender as RadMessageBoxForm;
    box.Location = new Point((this.Location.X + this.Width / 2) - (box.Width/2), (this.Location.Y + this.Height / 2 )- (box.Height/2));  
    
}

To reproduce:

public partial class RadRibbonForm1 : Telerik.WinControls.UI.RadRibbonForm
    {
        public RadRibbonForm1()
        {
            InitializeComponent();
            this.AllowAero = true;
            this.RibbonBar.QuickAccessToolbarBelowRibbon = false;
        }
    }

Note: the system buttons not always handle the mouse click.

Workaround: set AllowAero to false OR RibbonBar.QuickAccessToolbarBelowRibbon to true.

How to reproduce: create a DPI-aware application and set the AllowAero property of the ribbon form to false, the titlebar will not be themed

Workaround: override the ScaleControl method of in the RadRibbonForm instance in the project
Protected Overrides Sub ScaleControl(ByVal factor As SizeF, ByVal specified As BoundsSpecified)
    MyBase.ScaleControl(factor, specified)

    If Me.HasOwnToolbar AndAlso Me.AllowTheming AndAlso Not Me.IsDesignMode AndAlso Me.IsInitialized Then
        Me.AllowTheming = False
    End If
End Sub

Please refer to the attached sample project.
 
Workaround: Initialize the form just before showing it.

To reproduce: follow the steps from the attached gif file.

Workaround:

        public RadForm1()
        {
            InitializeComponent();

            ((RadRibbonFormBehavior)this.FormBehavior).AllowTheming = false;
        }

To reproduce:
RadForm form = new RadForm();
form.WindowState = FormWindowState.Maximized;
form.Text = string.Format("Child {0}", MdiChildren.Length + 1);
form.MdiParent = this;
form.Show();

Hover the Form's title bar the tooltip should start flashing/blinking

Workaround:   
  Sub New()
         
        InitializeComponent()
        AddHandler RadMessageBox.Instance.LocationChanged, AddressOf MsgLocationChanged
    End Sub
    Private Sub MsgLocationChanged(sender As Object, e As EventArgs)
        RadMessageBox.Instance.Location = New Point(Me.Location.X + Me.Width / 2 - RadMessageBox.Instance.Width / 2, _
                                                    Me.Location.Y + Me.Height / 2)
    End Sub

 Use attached to reproduce.

The exception message: "A circular control reference has been made. A control cannot be owned by or parented to itself.".

Workaround:
Do not specify the owner when showing the message box.