Grid: Scroll to row/column only

[jgoz]

For FixedSizeGrid and VariableSizeGrid, is there a way to only scroll to a particular row OR column index?

I.e., scroll to row 50 while maintaining the current horizontal scroll position.

This kind-of works with FizedSizeGrid by using scrollToItem({ rowIndex: 50, columnIndex: -1 }), but I'm thinking this just happens to work and is not valid. Trying the same with VariableSizeGrid causes an exception.

Specifying columnIndex: 0 works if the first column does not overflow the outer container, but if it is wider than the container, it will alternate between scrolling to the end of that column and the beginning of the column with align: "auto".

The ideal scenario for my use case would be making rowIndex and columnIndex optional. If either one is not specified, then scrollLeft or scrollTop would not be changed from the previous value.

If you would accept a PR for this suggestion I'd be happy to open it.

[bvaughn]

I'd be happy to review a PR if it includes all of the following:

• Minimal impact on bundle size (should probably only add two conditionals really)
• Includes tests
• Includes documentation changes