Since setting a clip is mandatory for almost all widgets, we can as well
change the size-allocate signature to include a out_clip parameter, just
like GtkCssGadget did. And since we now always propagate baselines, we
might as well pass that one on to size-allocate.
This way we can also make sure to transform the clip returned from
size-allocate to parent-coordinates, i.e. the same coordinate space
priv->allocation is in.
We now rely on toplevels receiving and forwarding all the events
the windowing should be able to handle. Event masks are no longer a
way to determine whether an event is deliverable ot a widget.
Events will always be delivered in the three captured/target/bubbled
phases, widgets can now just attach GtkEventControllers and let those
handle the events.
Add a new ::measure vfunc similar to GtkCssGadget's that widget
implementations have to override instead of the old get_preferred_width,
get_preferred_height, get_preferred_width_for_height,
get_preferred_height_for_width and
get_preferred_height_and_baseline_for_width.
We only keep one align flag per child, so it seems odd to
keep separate h/v expand flags. Just keep one expand flag
and interpret it according to orientation. Allow setting
the expand flag for child widgets too, though, so we can
make widget expand without interfering with the recursive
widget expand flag.
Update all callers.
Use the new possibility of expanding child widgets to make
the label of check and radio buttons expand. This fixes
unexpected behavior of these widgets in RTL in some places.
https://bugzilla.gnome.org/show_bug.cgi?id=765742
Since we are really only interested in the center point of the
slider allocation, the pre-computed slider geometry is perfectly
fine, just use it always. This avoids the complication with
gadget visibility.
The slider gadget may be turned invisible as side-effect of
gtk_range_calc_slider(). If that happens,
gtk_css_gadget_get_content_allocation() returns { 0, 0, 0, 0},
which leads us to calculate a negative allocation for the highlight
node. Avoid this, by just reusing our already calculated slider
allocation in this case (it is not technically the same as the
content, allocation, but the difference hardly matter here.
https://bugzilla.gnome.org/show_bug.cgi?id=764022
