Excel-like behavior with up/down cursors

This grid is amazingly similar to Excel, but one difference is that hitting a cursor key in Excel commits the value and moves in the appropriate direction. Tab and enter (and even shift-tab etc!) are equal in behaviour.

Excel has interesting selection behaviour actually. If you just type and hit an arrow etc, it's almost the cells are in a 'quick entry' mode and you can quickly fly through entering values. But, if you then click on the typed characters, you end up in a 'textbox' mode where left/right cursors move between characters in that cell instead of jumping between cells.

Anyway, given how close it is to having the same behaviour it'd be nice to bring them in line at some point.

Thanks

Start by locating the grid's keyboard handling for arrow, Tab, Enter, and Shift-Tab actions, then inspect how cell editing switches between quick-entry and text-editing modes. Compare the current behavior with the requested Excel cases and add focused coverage for committing values, moving cells, and in-cell cursor movement. Done means these interactions consistently match the described behavior.