Lumiera GUI style and theming
=============================


'this page collects some pieces of information regarding the visual appearance of the Lumiera GTK GUI'

GTK-3 styles
------------
Styling of GTK-3 interfaces is based on CSS, with some specific conventions about the selectors
and some additional makro functions to generate colours and gradients. When GTK actually renders a widget,
id consults a 'strategy object' known as *Theme Engine*, passing it the region to draw in a abstracted way.
The Theme Engine in turn uses a '``style provider''' to retrieve the generic style properties it uses for drawing.
Thus, the Theme Engine defines the actual meaning of any style and is in the position to understand and thus
introduce additional engine specific styles and settings.

GTK-3 supports the powerful 'cascading' and 'contextual selectors' from CSS. Thus the nesting of elements
in the GUI forms the base for creating styling rules. Obviously it is preferrable to keep those rules
generic; we may refer to individual gui elements by name (`#ID`) though.

Recommended reading
~~~~~~~~~~~~~~~~~~~
 * for technically precise coverage, consult the pages
   https://developer.gnome.org/gtk3/3.4/GtkCssProvider.html[GtkCssProvider]
   and
   https://developer.gnome.org/gtk3/3.4/GtkStyleContext.html#gtkstylecontext-classes[predefined style classes]
   in the GTK-3 reference manual.
 * to start, look at this http://thegnomejournal.wordpress.com/2011/03/15/styling-gtk-with-css/[introductory text],
   or the more http://worldofgnome.org/making-gtk3-themes-part-1-basics/[hands-on series of articles from world of gnome]
 * this http://forums.fedoraforum.org/showthread.php?t=281568[post from fedora forum] features a conciese description
   of the task of theme creation
 * to understand the old (now obsolete) GTK-2 stylesheets, you might
   http://orford.org/gtk/[look here]