In v14.6.2, when you click on a cell, that cell is highlighted with the selection box.
https://jsfiddle.net/wkuehler/ka1s7pev/3/
In v15.0.x, when you click on a cell, that cell is in focus, i.e. you can type to edit the cell, the column headers are highlighted, the current row/col classed are added, etc., but the cell itself is not highlighted with the selection box.
https://jsfiddle.net/wkuehler/syrqcd4m/2/