This creates a new GtkTextViewChild that can manage overlay children at
given x,y offsets in buffer coordinates. This simplifies GtkTextView by
extracting this from GtkTextWindow as well as providing a real widget for
the borders.
With this change, we also rename gtk_text_view_add_child_in_window() to
gtk_text_view_add_overlay(). For those that were using
GTK_TEXT_WINDOW_WIDGET, they can use a GtkOverlay. It does not appear
that anyone was using GTK_TEXT_WINDOW_(LEFT|RIGHT|TOP|BOTTOM) for widgets
in this fashion, but that can be done by setting a gutter widget with
gtk_text_view_set_gutter(). We can make GtkTextViewChild public if
necessary to simplify this should it become necessary.
GtkTextViewChild will setup a CSS node of either "text" or "border"
depending on the GtkTextWindowType.
The old GtkTextViewChild has been renamed to AnchoredChild as it is only
used for widgets with anchors in the GtkTextBuffer. This also removes the
use of allocated GSList and instead embeds a GQueue and GList to save a
few extraneous allocations.
Make the transform (transfer full).
1. This makes sure we actually reference the transform. Previously we
did not.
2. Most callers create a new transform to pass to us. Now they don't
have to uref it anymore.
That test was cool in 2011, but hasn't been updated or used since then
because its features are now part of widget-factory and the inspector.
So let's remove it.
This library is meant to be the new CSS library that gets used from GDK,
GSK and GTK for string printing and parsing.
As a first step, move GtkCssProviderError into it.
While doing so, split it into GtkCssParserError (for critical problems)
and GtkCssParserWarning (for non-critical problems).
This will be used to let the inspector and other users
pick insensitive widgets again. For now, update all
callers to pass no flags, preserving the current
behavior.
The need of a specialised fixed layout container that can be placed into
a GtkScrolledWindow ceased to exist once GtkScrolledWindow gained the
ability to automatically interpose a GtkViewport when adding a child
that does not implement GtkScrollable.
All the other justifications that led to the existence of GtkLayout as a
separate widget from GtkFixed have been largely made irrelevant in the
20 years since its inception.
