Instead, add a function gtk_image_set_icon_size() for the cases where
overriding the icon size is necessary.
Treat icon sizes the same way as pixel sizes, too. So gtk_image_clear()
no longer unsets the icon size.
Instead of returning the icon size with them, make
gtk_image_get_icon_name() and gtk_image_get_gicon() only return the icon
itself.
As a benefit, we can turn them into regular getters that return values
instead of requiring out parameters.
Instead, provide gtk_image_get_icon_size() to query the icon size.
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.
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 don't need to care in this case since the default values should
always be assumed to be 0, and setting a baseline of 0 is just wrong
when orientation == HORIZONTAL, it should be -1 (or unset).
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.
The event shall no longer be "directed" to the event window, but the
widget. Getting a enter/leave event is enough now to know whether the
pointer is inside or outside the widget.
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.
The custom gadget draw function has the side effect of informing
the gadget machinery wether to draw focus or not. Bring the
draw function back, just for its boolean return value. We may
want to find a better solution for this.
