If a subclass (say a child of GtkButton) overrides the non-baseline
size request methods we need to call these, rather than the new
get_height_and_baseline_for_width method.
In order to handle this we make the default for this method to be
NULL, and instead check at runtime which method to call. If any
non-baseline vfunc has changed in a class but the baseline one
hasn't, then we can't use the baseline one.
We now report any baselines from the child, and allocate it.
Also, in the case of a baselign aligned child we ignore yscale/yalign
as that is not supportable.
Report a baseline based height and baseline whenever there
are children with ALIGN_BASELINE.
Assign baseline to childen in size_allocate. Either the one inherited
from the parent if set, or otherwise calculate one based on any
ALIGN_BASELINE children.
This modifies the size machinery in order to allow baseline support.
We add a new widget vfunc get_preferred_height_and_baseline_for_width
which queries the normal height_for_width (or non-for-width if width
is -1) and additionally returns optional (-1 means "no baseline")
baselines for the minimal and natural heights.
We also add a new gtk_widget_size_allocate_with_baseline() which
baseline-aware containers can use to allocate children with a specific
baseline, either one inherited from the parent, or one introduced due
to requested baseline alignment in the container
itself. size_allocate_with_baseline() works just like a normal size
allocation, except the baseline gets recorded so that the child can
access it via gtk_widget_get_allocated_baseline() when it aligns
itself.
There are also adjust_baseline_request/allocation similar to the
allocation adjustment, and we extend the size request cache to also
store the baselines.
Setting this means baseline aware containers should align the widget
according to the baseline. For other containers this behaves like
FILL.
In order to not suprise old code with a new enum value we always
return _FILL for _BASELINE unless you specifically request it via
gtk_widget_get_valign_with_baseline().
Instead of having three different boxes and style classes, we can just
get away with the regular background box, plus a window-frame, which
contains the external frame, together with the window drop shadows.
GtkWindow now has special code to ensure the backing actual window is
allocated big enough to accomodate the shadows (using the shadow size
calculations introduced in the previous commit). We also use the margin
value to determine the size of the invisible borders (which can then be
different than the shadow).
