Re: Gtk3 and theming - a proposal (with code)

["Robert Staudinger" <robert staudinger gmail com>]

On Mon, Oct 13, 2008 at 4:58 PM, Alberto Ruiz <aruiz gnome org> wrote:

[...]

>> It would also be possible to introduce aliases for the sake of
>> theming, e.g. "GtkTreeViewColumnHeader" for a GtkButton inside a
>> treeview. Maybe such an approach would be feasible to bridge the gaps
>> between the "widget access" and the "no widget access" camps?
>
> That's exactly the kind of thing that we want to propose. That's why
> we need something richer and more flexible than the detail string. If
> a column header button is rendered, the engine should not by any means
> crawl the structure to figure it out. The api call should have that
> information out of the box.

There are two different cases of parent-matching to consider. One is
for composite widget where, agreed, it may not be desireable to depend
on implementation details. QT introduces the notion of "sub-controls"
[1] for that, a thing we are also discussing for the CSS engine.

The other case is "legitimate" parent/position matching, for example
to theme buttons inside a button box (see [2] for a mockup) or
even/odd row colouring in a treeview. It would be on the one hand
prone to limit designers' possibilities by restricting that second
variant in any way, and on the other hand hard to provide a complete
representation of a window's widget hierarchy. Here iteration through
parent widgets is needed.

[1] http://doc.trolltech.com/4.5/stylesheet-syntax.html#sub-controls
[2] http://www.gnome.org/~robsta/gtk-css-engine/screenshots/child-index-selector.png

- Rob