Unified themes/icons/fonts

we may run into 6 combinations of problems about theming in linux:
1. common user in Gnome runs KDE/QT apps
i don't know if a "qt-gtk-engine" exists. anyway, use kcontrol or qtconfig to config themes of qt apps.

2. common user in Gnome runs KDE/QT apps with privileges
equivalent to 6

3. common user in Gnome runs Gnome/Gtk1/Gtk2 apps with privileges
symbolic link ~/.themes ~/.icons ~/.gtkrc-2.0 in root home

4. common user in KDE runs Gnome/Gtk1/Gtk2 apps
install gtk-qt-engine theme engine. it's a normal gtk theme engine by using current qt theme ;) furthermore it will also install a kcontrol module, so that you can config it in kcontrol.
problem: menu of gtk apps is rendered black. probably due to the transluecy feature i enabled in qt.

5. common user in KDE runs Gnome/Gtk1/Gtk2 apps with privileges
equivalent to 3

6. common user in KDE runs KDE/QT apps with privileges
symbolic link ~/.qt ~/.kde/share/icons ~/.kderc ~/.fonts in corresponding postions of root home. configure theme by running kcontrol as root if yet no effect.

summary:
the general idea here is, symbolic linking all theme related data to root home so that privileged apps can use the current theme/icon/font. furthermore, changing the current theme will directly reflect to the root apps.

for qt style -> gtk, gtk-qt-engine is used, though yet some bugs.
for gtk theme -> qt, not sure if similar engine exists.