Работа с классом System.Windows.Controls.RichTextBox
Почему при попытке создания объекта класса private System.Windows.Controls.RichTextBox a1; выскакивают четыре следующих ошибки?
(reference на PresentationFramework.dll добавлена)
Error 1 The type 'System.Windows.Markup.IAddChild' is defined in an assembly that is not referenced. You must add a reference to assembly 'PresentationCore, Version=4.0.0.0, Culture=neutral, PublicKeyToken=31bf3856ad364e35'. D:\Docs_Pletnyov\VS_CS\Soft\My_projects\WindowsFormsApplication2\WindowsFormsApplication2\Form1.Designer.cs 59
Error 2 The type 'System.Windows.Markup.IQueryAmbient' is defined in an assembly that is not referenced. You must add a reference to assembly 'System.Xaml, Version=4.0.0.0, Culture=neutral, PublicKeyToken=b77a5c561934e089'. D:\Docs_Pletnyov\VS_CS\Soft\My_projects\WindowsFormsApplication2\WindowsFormsApplication2\Form1.Designer.cs 59
Error 3 The type 'System.Windows.IInputElement' is defined in an assembly that is not referenced. You must add a reference to assembly 'PresentationCore, Version=4.0.0.0, Culture=neutral, PublicKeyToken=31bf3856ad364e35'. D:\Docs_Pletnyov\VS_CS\Soft\My_projects\WindowsFormsApplication2\WindowsFormsApplication2\Form1.Designer.cs 59
Error 4 The type 'System.Windows.UIElement' is defined in an assembly that is not referenced. You must add a reference to assembly 'PresentationCore, Version=4.0.0.0, Culture=neutral, PublicKeyToken=31bf3856ad364e35'. D:\Docs_Pletnyov\VS_CS\Soft\My_projects\WindowsFormsApplication2\WindowsFormsApplication2\Form1.Designer.cs 59
А на остальные две сборки?