This is reproducible when you disable the automation peers by setting the AutomationManager.AutomationMode static property to Disabled.

It happens when you open a new RadWindow dialog (using the ShowDialog method), and the close it. After this, when you interact with the main window (click a button, hover a GridView, etc.) the exception occurs.

The exception is thrown only in the Output pane of Visual Studio and it doesn't cause any harm to the application. You can safely ignore it.

The exception message is "Invalid window handle".

To work this around you can enable the "Enable Just My Code" option in Visual Studio.

Select an item with mouse, scroll thousands of items down and then shift select item to perform range selection. This will block the UI thread for seconds. 

To reproduce this use the following code snippet:

Steps to reproduce:

1. Start a new connection from Shape 1, by dragging one of its connectors.
2. Drag the connection over Shape 2. 

Expected: The connector closest to the mouse should get highlighted and when you drop the connection it should get attached to the shape.
Actual: The closest connector is not highlighted. Also, when you drop the connection over the target shape it doesn't get attached.

If set the AutoCompleteMode property in a Style Setter, and exception is thrown.

To work this around set the property directly on the control.
<telerik:RadMultiColumnComboBox AutoCompleteMode="Search" />

Most commonly the exception message is "Input file or data stream does not conform to the expected file format specification".

This appears because of the glyphs font used in the different controls.

To work this around you can use two approaches:

• Update to Windows 7 SP2.
  
  
• The second option is to download the UI for WPF source code, find the TelerikWebUI.ttf file and convert it to .otf using a third party tool (like FontForge for example). Then use a reflection to replace the font file, before the application startup. For example:
  
  RadGlyph.GetRegisteredFonts();

  var dictionary = typeof(RadGlyph).GetField("registeredTypefaces", BindingFlags.NonPublic | BindingFlags.Static)?.GetValue(null) as Dictionary<string, Typeface>;

  dictionary?.Clear();

     

  RadGlyph.RegisterFont(new FontFamily(new Uri("pack://application:,,,/WpfApp3;component/TelerikFont/", UriKind.RelativeOrAbsolute), "./#TelerikWebUI"), "TelerikWebUI");
  In the code snippet, "WpfApp3" is the assembly name of your project, and "TelerikFont" is a folder in your project, containing the converted font file. You can call this code in the OnStartup override of App.xaml.cs. Or before the InitializeComponent() call in the main window's constructor.

Moving a window fast on low performance machine or between two monitors causes incorrect offset to be applied to the mouse cursor

The ImagesDeflaterCompressionLevel and ContentsDeflaterCompressionLevel in the PdfFormatProvider's export settings have 0 for default value instead of -1.

Workaround: Change the settings's properties to -1 explicitly.

On export to HTML tab stops are converted to non-breaking spaces ( ). Sometimes the width of the all nbsp-s becomes different than the width of the tab stop. When document which contains grid-like data is exported to HTML its columns are not aligned.

The RadWindow's size shrinks while dragging it on a monitor with high DPI scale which causes it to shake a bit. In other words, the dragging is not smooth.

This was reproduced on a monitor with DPI scale set to 175%.
This is reproducible if you set the RadWindowInteropHelper.AllowTransparency on the RadWindow control (regardless of the value - True or False).
This is more noticeable in .NetCore projects.

See attached picture together with these steps.

1. select a item in the list
2. import multiple other items in one go -> the last imported item is marked as selected (this is OK), the previously selected item is no longer marked as selected (this is OK).
3. SHIFT select the first item of the ones imported in step 2 -> the items between the last imported item and the first imported item are selected, but the item that was selected in step 1 is now also selected...

Thanks in advance!

Bart