This is just a starting point, to be turned into a real Transform
element later, along with syntactic sugar to turn rotation, etc. into a
transform matrix in the generated output.
This allows filling glyphs with gradients. However femtovg
appears to apply the start/end position per-glyph
instead of globally - resulting in a different result than Qt.
Add support for built-in property aliases and rename `color` to
`background` - in preparation for it also changing to type brush.
Right now the alias is silent, a deprecation and overall change
will come in a subsequent change.
This intends to provide a configurable rectangular "drop shadow". The
API is modeled after CSS/HTML5 Canvas where the element can be "bound"
to an existing rectangular shape (geometry and radius), the offset can
be used to place the shadow and color and blur configure the shadow.
The shadow's color fades into transparent.
TODO (in subsequent changes):
* Documentation
* Qt implementation
This also makes the focus() method available as a member function on any
item, but the resolve_element_reference_in_set_focus_calls() pass will
check if the elements are valid.
The check for `has-focus` to determine a focusable item was replaced
with an annotation on the built-in elements, so that `has-focus` can
later be implemented as a built-in function through the run-time,
without the need for a boolean property.
Ideally we would put the bindings dirrectly in the builtins.60
But this is unfortunately not possible because the "StyleMetrics" is not
yet available there and that would be a circular dependencies.
This allows implementing another sliding puzzle theme feature, the
boldness of the tile number text in the simple theme when the tile is in
the correct position. For the other themes the weight is constant and
it's bold.
More cleanup to follow later: unify the font handle and FontCacheKey
handling, improve the API to allow for the use of symbolic constants
(normal, bold, etc.) instead of the CSS number values.
