Basic instructions for compiling:

  cd oxygen-gtk
  mkdir build
  cd build
  cmake ../
  make -j2
  sudo make install

Notes:

1/ using cmake alone (with no argument) should usually work (that is: select the right path for installing the theme)
If one wants to customize this path, on can manually set the CMAKE_INSTALL_PREFIX flag when running CMake. 
The default is equivalent to:

  cmake -DCMAKE_INSTALL_PREFIX=`pkg-config --variable=prefix gtk+-2.0` ../

2/ when using the default installation prefix, the theme engine should also automatically get installed in
the correct location. However, if a custom CMAKE_INSTALL_PREFIX location is set, an extra flag is needed at
the CMake stage, to compile oxygen-gtk on a 64 bits machine (for instance): 

  cmake -DCMAKE_INSTALL_PREFIX=your_path -DLIB_SUFFIX=64 ../

For other types of architectures (except, notably, i386) it might also be necessary to set the proper value for LIB_SUFFIX. 
It is left to the user to figure which value must be used.

3/ make -jX uses X parallel jobs so that compilation would speed up on SMP machines with X cores/CPUs/threads

4/ There are some build settings available in /CMakeLists.txt:

    * OXYGEN_DEBUG:
set this to 1 to enable a large amount of debug information to be printed to terminal

    * OXYGEN_ICON_HACK:
set this to 0 to disable oxygen-gtk from forcing KDE icons for GTK apps (regardless of DE)

    * OXYGEN_FORCE_KDE_ICONS_AND_FONTS:
set this to 0 to disable forcing KDE icons and fonts (and use the ones set in GTK) - makes sense only when
KDE is not running. Doesn't change anything when KDE is running.

    * ENABLE_COMBOBOX_LIST_RESIZE:
set this to 0 to disable combobox list resizing (see README for more detail)

    * ENABLE_INNER_SHADOWS_HACK
set this to 0 to disable rendering of inner shadows using off-screen pixmap of composite widgets
Note: this flag is automatically set to zero if gtk version is too old because of upstream bugs.

    * ENABLE_GROUPBOX_HACK
set this to 0 to disable rendering of groupbox consistently with Qt. 
This special rendering might triggers some unwanted size-changes events in some dialog the first time they are
made visible.