This patch adds the GtkScrollablePolicy type property to GtkScrollable
and implements it in all subclasses. GtkScrolledWindow observes this
property to make a good guess about when to show/hide scrollbars for
height-for-width content.
Most scrollable children do not do height-for-width *yet* but
most certainly will (toolpalette, treeview, iconview, textview
widgets all TODO), for scrollable widgets that do have a minimum
and natural size, it's important for them to observe the state
of this property in order to properly drive the scroll adjustments
according to the desired GtkScrollablePolicy. This patch makes
GtkViewport do this.
Patch also adds tests/testscrolledwindow.c to display the effects
of this property.
Added the child list to GtkCellAreaBox, added _pack_start() and
_pack_end() apis to GtkCellAreaBox since they are appropriate there
and implemented GtkCellLayoutIface to override the _pack_start()/end()
methods (since the base GtkCellArea class simply forwards these apis
to the generic ->add() api on the base class).
Now GtkCellArea handles attribute connections in the base class,
subclasses only need to add/remove the renderers, render them,
do geometry and handle events.
Now GtkCellArea provides a generic way of applying attributes
from a GtkTreeModel/GtkTreeIter, GtkCellArea bookkeeps a hashtable
of GtkCellLayoutDataFunc's and completely abstracts the applying
of data to cells... GtkCellArea implementations need only to bookkeep
the added renderers and attributes (probably we can abstract the
attribute bookkeeping in the base class as well).
Things starting to take a good and practical shape.
The scrollable patch removed set_scroll_adjustments (NULL, NULL) from
gtk_tree_view_init() which ensured the treeview would have adjustments
at all times, this patch adds set_v/hadjustment (NULL) to _init to ensure
the same thing (without it, there are crashes when trying to access the
adjustments notably from set_headers_visible() in gedit).
I.e. Since we are now calling get_preferred_width() to ensure a good 'for_size'
for get_height_for_width() we need to avoid warning about this internal expected
recursion.
