public static void Test(this RichTextBox richTextBox)
{
IntPtr hWnd = richTextBox.Handle;
ITextDocument textDocument = GetTextDocument(richTextBox);
string name = textDocument.GetName();
float tabStop = textDocument.GetDefaultTabStop();
int n1 = textDocument.Freeze();
int n2 = textDocument.Unfreeze();
Marshal.ReleaseComObject(textDocument);
}
