This is where it gets hairy.
Some quick settings items will have an associated menu. When
opened, the main menu should grow to make room for the child
menu, as it would do if it contained the child.
At the same time, the child menu will attach to its parent, and
block all input there while it is open.
Menu-modal menus so to speak.
Implement this as follows:
- change the QuickSettingsMenu actor to a stack that holds
- the boxpointer (a.k.a. the actual menu)
- an overlay actor to hold child menus
- use constraints to bind the overlay's position and width
to the boxpointer; the y position is offset to align the
overlay with the grid inside the actual menu
- add a placeholder actor to the main grid, whose height is
bound to the overlay height; using a "clone" instead of
the actual overlay means that layout changes are not triggered
from outside the grid hierarchy, which would be prone to
allocation warnings
- update the layout manager to not allocate the placeholder as
a regular grid child, but instead include its height in the
space underneath the row with an open menu
- apply a dim effect to the boxpointer when a child menu is
open, to indicate that input is blocked
Part-of: <https://gitlab.gnome.org/GNOME/gnome-shell/-/merge_requests/2393>
The quick settings menu is a popover that arranges items in a
reflowing, homogeneous grid. Grid children may span multiple
columns, but not rows.
For now the QuickSettingsMenu that contains the grid is just a
convenience wrapper around the layout manager that does the heavy
lifting. The two will become more intertwined when we add support
for menu toggles though, so the custom menu type is unfortunately
needed.
Part-of: <https://gitlab.gnome.org/GNOME/gnome-shell/-/merge_requests/2392>
