When a background video was used in a mega menu, it was only working in
edit mode. Indeed, the background video size is computed on page load
(and on window resize) but as the video is inside a hidden dropdown
menu in this case, the size cannot be properly computed.
This commit fixes the issue by recomputing the video size on dropdown
menu opening.
task-2080590
closesodoo/odoo#38314
X-original-commit: 66ec1c19b63fe26e559ed2d8d7359df974ade789
Signed-off-by: Quentin Smetz (qsm) <qsm@odoo.com>