To reproduce:
- Set the ParagraphDefaultSpacingAfter to 1.
- Start the application and add a comment directly.

The issue exist when there is many comments as well. The comment balloons should have minimum size and should not overlap eachother.

Workaorund:
void radRichTextEditor1_CommandExecuting(object sender, CommandExecutingEventArgs e)
{
    if (e.Command is InsertCommentCommand)
    {
        int paragaphs = radRichTextEditor1.Document.Sections.First().Blocks.Count();

        if (paragaphs <= 1)
        {
            radRichTextEditor1.InsertLineBreak();
        }

    }
}