Steps to reproduce

1. install Ibexa 4.6.3
2. Edit or create some landing page content
3. Place any block in the drop zone
4. Scroll the window so that when hovering over the block, there is almost no space left at the bottom of the window
5. Open the blocks context menu (three dots icon)

Result
The context menu opens detached from the trigger element.

Expected result
The context menu is aligned with the trigger element.