Get the elements size also on mousedown. Because before that, the size was only obtained on the start method when some elements did not yet have its actual size. Example: elements in inactive slides in the carousel snippet. task-2162952 closes odoo/odoo#48193 X-original-commit: 2a36c684bb33704e46a6f30b5c501043683da67d Signed-off-by: Quentin Smetz (qsm) <qsm@odoo.com>