Wojciech Szymański

Improving performance of row and column calculators

1

### Description PR https://github.com/handsontable/handsontable/pull/7625 showed that change in number of columns added as offset to calculator may result in performance boost. There is possibility that we can do even more...

Fixed problem with overwriting merged cell value + added possibility for stoping `modifyData` hook propagation

5

### Context I've found that there is done some date overwriting by the below code. https://github.com/handsontable/handsontable/blob/4f6c253e6257514b168a4c98fe35c9c233b1487b/handsontable/src/plugins/mergeCells/mergeCells.js#L248-L250 This is an intended action. The `MergeCells` plugin fills up some cells with `null`...

### Description As described in the title, it seems that methods [colToProp](https://handsontable.com/docs/7.4.2/Core.html#colToProp) and [propToCol](https://handsontable.com/docs/7.4.2/Core.html#propToCol) may not work properly. They don't return `null` values for indexes beyond the table boundaries. It...

Updated demos to React 18

6

### Context Done changes: - [x] Updated `docs/react-data-grid/demo/` and `/react-data-grid/redux` pages (they have been importing `react-dom`). - [x] Updated examples project in the directory `examples/next/docs/react`. - [ ] Updated visual...