When importing a XAML document that contains a Content control with PrefixMappings to its TextProperties` DataBinding an exception is thrown: 'Telerik.Windows.Documents.Model.StructuredDocumentTags.DataBinding.PrefixMappings' threw an exception.'

To reproduce:

1. Insert content spanning 3 pages
2. Ensure a single page is visualized in the viewport 
3. Start selecting from the beginning of the content till the end by dragging the mouse
4. Press Delete

The issue is a regression introduced in R3 2021 SP1.

Having two mention providers and using the second right after using the first one actually loads the source of the first provider.

Exception when importing a document with an empty table.

Workaround: Remove the empty tables:

DocxFormatProvider provider = new DocxFormatProvider();
var doc = provider.Import(File.ReadAllBytes(@"C:\Users\mpc\Downloads\22-51.docx"));

foreach (var section in doc.Sections)
{
    var tables = section.EnumerateChildrenOfType<Table>();
    foreach (var table in tables.ToList())
    {
        if (table.Rows.Count == 0)
        {
            section.Blocks.Remove(table);
        }
    }
}
radRichTextBox.Document = doc;

Hello,

In the attached example, applying character formatting to a selection that ends between two annotation ends and undoing the formatting action does not revert the annotations to the exact position as they were before the formatting was applied.

Applying formatting twice and undoing twice crashes the editor because the second undo command inserts unpaired annotations (as it operates on a document state different than the expected one).