'Declaration
Public Class C1LineSpacingTool Inherits C1.WPF.RichTextBox.Ribbon.RichTextBoxSelectTool(Of Nullable(Of Double)) Implements IUpdateableTool
public class C1LineSpacingTool : C1.WPF.RichTextBox.Ribbon.RichTextBoxSelectTool<Nullable<double>>, IUpdateableTool