In [1], the resizing and the drag and drop of a grid item both put it in front of all the other items and in front of the background grid (thanks to the `z-index` property). This commit changes that behavior: now, the grid item stays at the same z-index if we are resizing it or if we are dragging it over the grid from which it is coming. In the case of a drag over an other grid, it is placed in front of all its grid items. In all these cases, the grid item is placed behind the background grid. [1]: https://github.com/odoo/odoo/pull/93144 task-2973198 closes odoo/odoo#102525 X-original-commit: 67d1b078329600efce414974307d74e9fa9ba9fe Related: odoo/design-themes#601 Signed-off-by: Quentin Smetz (qsm) <qsm@odoo.com>