public void Insert(int offset, string text)
{
if (readOnly)
{
return;
}
OnDocumentAboutToBeChanged(new DocumentEventArgs(this, offset, -1, text));
textBufferStrategy.Insert(offset, text);
lineTrackingStrategy.Insert(offset, text);
undoStack.Push(new UndoableInsert(this, offset, text));
OnDocumentChanged(new DocumentEventArgs(this, offset, -1, text));
}