Those worked similarly to those in GtkFlowBox, but would additionally
handle "active" state for child rows. Simplify this to just enabling/
disabling active state on gesture press/release, we don't get the
nice state updates when hovering around with a mouse button pressed,
but the rationale from flowbox applies here, and makes a nice cleanup.
They just maintain priv->in_button and widget state up-to-date, this
basically matters during user interaction, and is already maintained
in the gesture ::update handler. This seems to be sufficient.
Those basically controlled priv->active_child_active, which would
1) trigger a redraw when the pointer enters/leaves it, and 2) ensure
that press/release happen on the same child for it to be activated.
The former is not necessary, and the latter can be simplified by
just checking again the child on the coordinates given by the
::release gesture handler. This makes all enter/leave/motion_notify
event handlers unneeded.
All kinetic scrolling initial velocity calculations are now
taken from the scroll controller. The handling of timeouts
to snap back when overshooting has been also made to just
apply on devices that can't emit ::scroll-begin/end.
This is a GtkEventController implementation to handle mouse
scrolling. It handles both smooth and discrete events and
offers a way for callers to tell their preference too, so
smooth events shall be accumulated and coalesced on request.
On capable devices, it can also emit ::scroll-begin and
::scroll-end enclosing all ::scroll events for a scroll
operation.
It also has builtin kinetic scrolling capabilities, reporting
the initial velocity for both axes after ::scroll-end if
requested.
This change is made for consistency, it doesn't make sense to expose
one-way propagation, as it can only break expectations from GTK+. This
function might be made entirely private in the future, but it still
makes sense to do this in one go for our internal usecases.
This will allow further cleanups and optimizations in capture/target/bubble
event delivery. For simplicity, ATM every widget will receive its own
GtkEventControllerLegacy, it could be desirable to add finer control over
this in the future, so widgets that fully use event controllers for input
management can do away without this legacy piece.
