[Solved] Problem with spellchecker suggestions in RadRichTextBoxes using custom ContextMenuContentBuilder

[Peter]

I have more than one RadRichTextBox with spellchecking turned on in a grid and I am providing my own ContextMenuContentBuilder.  When I highlight a misspelled word in the first RadRichTextBox and choose a suggestion from the context menu, the word is corrected but only the first letter of the word is displayed.  Subsequent clicking on the word causes a crash (Object reference not set to an instance of an object).  I have pasted in the MainPage of the project below to reproduce the bug.  Have I done something incorrectly?  If not, are there any workarounds available?  If no workarounds, will there be a fix soon?  Thanks.

public partial class MainPage : UserControl
    {
        public class CustomContextMenuContentBuilder : ContextMenuContentBuilder
        {
            public CustomContextMenuContentBuilder(RadRichTextBox richTextBox)
                : base(richTextBox)
            {
            }
        }

        public MainPage()
        {
            InitializeComponent();

            LayoutRoot.Children.Add(CreateRichTextControls(0, 0));
            LayoutRoot.Children.Add(CreateRichTextControls(1, 1));
        }

        private RadRichTextBox CreateRichTextControls(int row, int col)
        {
            RadRichTextBox control = new RadRichTextBox();
            control.HorizontalAlignment = HorizontalAlignment.Stretch;
            control.VerticalAlignment = VerticalAlignment.Stretch;
            control.Background = new SolidColorBrush(Colors.LightGray);

            control.SetValue(Grid.RowProperty, row);
            control.SetValue(Grid.ColumnProperty, col);

            Telerik.Windows.Controls.RichTextBoxUI.ContextMenu contextMenu = (Telerik.Windows.Controls.RichTextBoxUI.ContextMenu)control.ContextMenu;
            contextMenu.ContentBuilder = new CustomContextMenuContentBuilder(control);

            return control;
        }
    }

[Boby]

Hello Peter,
Thank you for this excellent report. The incorrect behavior is caused by the fact that context menu is loaded by MEF - this makes one ContextMenu instance shared between multiple RadRichTextBoxes,  causing context menu's CustomContextMenuContentBuilder to be associated with the second RadRichTextBox. This is considered a bug, and hopefully will be fixed in next major release.
As a simple workaround, you can instantiate your context menus manually and do not rely on MEF:

private RadRichTextBox CreateRichTextControls(int row, int col)
{
    RadRichTextBox control = new RadRichTextBox();
    control.HorizontalAlignment = HorizontalAlignment.Stretch;
    control.VerticalAlignment = VerticalAlignment.Stretch;
    control.Background = new SolidColorBrush(Colors.LightGray);

    control.SetValue(Grid.RowProperty, row);
    control.SetValue(Grid.ColumnProperty, col);

    ContextMenu contextMenu = new ContextMenu();
    contextMenu.ContentBuilder = new CustomContextMenuContentBuilder(control);

    control.ContextMenu = contextMenu;

    return control;
}

We have added Telerik points to your account in appreciation. Don't hesitate to contact us if you have other questions.

Best wishes,
Boby
the Telerik team