Changing the DataSource or scrolling are slow.

Create a grid with more than 20 columns and add 5K rows for example. Maximize the form and try to scroll with mouse wheel. You will notice that the scrolling performance is worse compared to the normal state of the form with less visible visual elements.

Workaround: this.radGridView1.EnableFastScrolling = true; and use the scrollbar's thumb

Second workaround: use paging:  https://docs.telerik.com/devtools/winforms/gridview/paging/overview Thus, you will display as many rows as possible to display on the screen per page. Instead of scrolling, you will navigate through pages.

RadRichTextEditor renders the text with a little bigger characters spacing than RadRichTextBox and MS Word.
Note: this text spacing problem can be observed in other Telerik controls as well.

When UseCompatibleTextRendering property is set to false, the data cells overlaps the row header cells when horizontal scrolling is performed.

Controls in RadPanel redraw slowly when changing the Enabled state of the panel.

Workaround:

private void radButton1_Click(object sender, EventArgs e)
{
    if (this.radPanel1.Enabled)
    {
        this.radPanel1.Enabled = false;
    }
    else
    {
        this.radPanel1.Visible = false;
        this.radPanel1.Enabled = true;
        this.radPanel1.Visible = true;
    }
} 
 

On Windwos XP , Windows Vista, Windows 7 the RadForm/ShapedForm hides the taskbar when it is set to Auto-Hide. When you try to show the taskbar it appears behind (under) the RadForm instead of infront (over) it.

1. Create a new Form that inherits from RadForm and add some rad controls.
2. Checkin the file in your source control system
3. Open the form in design time will cause checkout

Please refer to the attached sample project. When you start the application the form's text indicates how many times the AppointmentFormatting event is fired for only 30 appointments - more than 400 times. The more appointments you have , the more times the vent is initially fired,e.g. if you have 50 appointmens it is fired If you switch between the different views you will see how the counter increases its value.

How to reproduce:
1. Run the Mail Merge example (QSF) 

2. Select the image inside the document and move it to another position

When a PDF document contains images compressed with CCITTFaxDecode with applied BlackIs1 parameter, black color is visualized as white and white as black.

Setting the RightToLeftLayout to true together with RightToLeft = Yes, cuts off the form

Use the code below.

1. Click the first button to insert a link.

2. Click inside the link to move the cursor.

3. Click the second button to insert the yellow rectangle

4. Click the third button to export the HTML content.

Actual result: StackOverflow exception occurs

        private void radButton1_Click(object sender, EventArgs e)
        {
            HyperlinkInfo info = new HyperlinkInfo()
            {
                NavigateUri = "http://www.google.com",
                Target = HyperlinkTargets.Blank,
                IsAnchor = false
            };
            this.radRichTextEditor1.InsertHyperlink(info, "www.google.com");
        }

        private void radButton2_Click(object sender, EventArgs e)
        {
            LightVisualElement button = new LightVisualElement();
            button.Text = "My Button";
            button.DrawFill = true;
            button.BackColor = System.Drawing.Color.Yellow;
            button.GradientStyle = Telerik.WinControls.GradientStyles.Solid;

            Section section = new Section();
            Paragraph paragraph = new Paragraph();
            InlineUIContainer container = new InlineUIContainer();
            RadElementUIContainer radContainer = new RadElementUIContainer(button);
            container.UiElement = radContainer;
            container.Height = 25;
            container.Width = 70;
            paragraph.Inlines.Add(container);
            section.Blocks.Add(paragraph);
            RadDocument doc = new RadDocument();
            doc.Sections.Add(section);
            radRichTextEditor1.InsertFragment(new DocumentFragment(doc));
        }

        private void radButton3_Click(object sender, EventArgs e)
        {
            Telerik.WinForms.Documents.Model.RadDocument document = radRichTextEditor1.Document;

            Telerik.WinForms.Documents.FormatProviders.Html.HtmlFormatProvider provider = new Telerik.WinForms.Documents.FormatProviders.Html.HtmlFormatProvider();

            provider.ExportSettings.InlineUIContainerExporting += ExportSettings_InlineUIContainerExporting;

            provider.ExportSettings.DocumentExportLevel = Telerik.WinForms.Documents.FormatProviders.Html.DocumentExportLevel.Fragment;
            provider.ExportSettings.ExportFontStylesAsTags = true;
            provider.ExportSettings.SpanExportMode = Telerik.WinForms.Documents.FormatProviders.Html.SpanExportMode.DefaultBehavior;
            string htmlValue = provider.Export(document);
            webBrowser1.DocumentText = htmlValue;
        }

        private void ExportSettings_InlineUIContainerExporting(object sender, Telerik.WinForms.Documents.FormatProviders.Html.InlineUIContainerExportingEventArgs e)
        { 
        }

Run the attached project on a monitor with 100% DPI scaling and open the Excel-like filter popup:

100%:

After moving the form to the second monitor with 150% DPI scaling, the filter popup is not OK:

150%:

The popup is smaller and smaller with each next opening (see the attached gif file) at 150%. If you decide to move back the form on the monitor with 100% DPI scaling, the filter popup is not scaled properly.

Currently, Tab selects the next control.

Attached is sample PDF document. 

I have a somewhat complex datasource with nested classes and collections of classes (called ReportConfiguration in my attached sample). I've created a sample app that illustrates the error when I try to databind using telerik controls; I get a runtime error that it cannot find one of the nested classes. Using standard .NET controls (FormMS), I do not get this error.

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();

If you dock a control in RadPanel, this control will cover the borders of RadPanel. This behavior is different from the behavior of the standard Panel behavior where the border is not covered, because of a Padding of 1.

We should consider whether this change should be introduced in our suite as this could modify the design of our customers' layouts in a way then don't want.

Workaround: this.radPanel1.Padding = new Padding(1);

1. Create RadRibbonForm and add code to start maximized 
2. Add status strip with some items on the ribbon form 
3. in the form constructor create a MDI child form, set it to start maximized and show it 
4. The result is that there is gap between the child form and the status strip

Workaround:
protected override void OnShown(EventArgs e)
{
    base.OnShown(e);
 
    this.WindowState = FormWindowState.Minimized;
    this.WindowState = FormWindowState.Maximized;
}