essence: 
easy custom design for non-techies:
	- infographics
	- step-by-step guides
	- reference guide
improved design structures:
	- cross-toolkit bridge

desktop environments
MATE, gnome2, gnome3, Gnome Flashback

toolkits	gtk2, gtk3, 

Window managers
metacity, unity?, emerald?, mutter?, enlightenment, sawfish, matchbox, Xfwm ...
List: https://en.wikipedia.org/wiki/Extended_Window_Manager_Hints

ICCCM specification 
Standard for interoperability between X Window System clients. Used for communication between normal clients and the window manager. Application programmers rarely work directly with the ICCCM itself but use the higher-level toolkit functions that implement it. 

EWMH
Efforts to update and clarify the ICCCM have resulted in the Extended Window Manager Hints. X Window System standard for window managers. Defines various interactions between window managers, utilities and applications.

The X Window System
Common on UNIX-like OS's. Provides the basic framework for a GUI environment: drawing and moving windows and interacting with a mouse and keyboard. X does not mandate the user interface — this is handled by individual programs.

Desktop environments
Xfce, Gnome Shell, KDE, LXDE, MATE, Unity, Enlightenment

window managers	usr/share/themes/*/xfwm4
themes	usr/share/themes/*/index.theme
icon sets	usr/share/icons/*/index.theme
		usr/share/icons/*/scalable/-
cursors	usr/share/icons/*/cursor.theme
		usr/share/icons/*/cursors/-
distribution logo 	usr/share/icons/*/scalable/apps/xfce4-panel-menu.svg
background images	desktop-base 
					Gustavo Franco <stratus@debian.org>
splash screen

widgets