Just in Time Loading in Spread .NET for WinForms

Background:

At times when working with large data, it is necessary to only load data for cells that are currently in view while simultaneously releasing memory occupied by cells that are no longer in view.

Steps to Complete:

1. Handle TopChange event of FpSpread and inside the event handler, calculate the current visible cell range as the grid scrolls vertically.

2. Handle LeftChange event of FpSpread and inside the event handler, calculate the current visible cell range as the grid scrolls horizontally.