Infinite scrolling - unstable

[ZapRiver]

I was able to successfully accomplish infinite scrolling in my application on pages that don't load too much data. However, the DataPreLoad event is firing too many times. So on pages where there are several thousands of records scrolling is slugging and the scrollbar unusable. It's hard to pull down the scrollbar's thumbnail without generating numerous DataPreload events, which in turn end up calling the database numerous times when it should really only fire once. To illustrate the issue, I have added two grids to the sample code. The first grid shows the skip and take values passed by the event, as well as a count that shows how many times the event is fired for a single scrolling event. The second grid shows the scroll event with the direction, position and a count of how many times the event is fired. Upon clicking the bottom arrow on the scrollbar, the scroll event fires sometimes 10 times and the DataPreload event sometimes twice.Clicking the scrollbar below the thumbnail brings a whole page of rows (which is normal) but the DataLoad event fires multiple times instead of just once, and the GridScroll event fires multiple times instead of just once. The result is that the data in the grid is totally unstable during a scroll and each time the DataPreload event fires, the API gets called (which means it gets called too many times), which makes infinite scrolling too slow and unpredictable. Clicking the down arrow on the scrollbar and leaving the mouse on it to scroll continuously is impossible without getting a headache. I have uploaded the source code on the same FTP site you provided last week.