The popup window would only be triggered by the alarm if/when the stock price would cross it, from either a "high alert" or a "low alert".
Let's say you entered 11 for high and 10 for low alerts. The stock is now at 10.50.
Once the price goes up above 11 (or down below 10), then the popup would show.
The hardest part is to make the whole thing triggered from "real-time" data.
If I could enter my own data, then I could input my own data provider, my real username and password. But there is no way I would share that with anyone else. Hence my dilemma. I have to do it myself as a standalone app sitting on my personal computer.
PS: Check out sStockquotes created by one of Donationcoders programmer. It's very good, but only offers delayed data.