The following code works
var mouseTracker = Observable.FromEventPattern<MouseEventArgs>(form1, "MouseMove");
//for Form1_MouseMove(object sender, MouseEventArgs e)
But how to make the Observable.FromEventPattern to take EventHandler <T> ? Something like
var mouseTracker = Observable.FromEventPattern<EventHandler<StockQuote>>(_board, "QuoteUpdated");
//for board_QuoteUpdated(object sender, StockQuote stockQuote)
Edit
Answer from Gluck works. I need to change the FromEventPattern to FromEvent.
var quoteObserver = Observable.FromEvent<EventHandler<StockQuote>, StockQuote>(
h => (_, sq) => h(sq),
eh => _board.QuoteUpdated += eh,
eh => _board.QuoteUpdated -= eh);