+-DWANT_(CORE|QTCLIENT|MONO)=(ON|OFF)
+ Choose which Quassel binaries to build.
+
+-DUSE_CCACHE=ON
+ Enable ccache if the ccache binary is available. This avoids the need for
+ hacks using PATH or the CXX variable to make ccache work.
+ Distributors may want to disable automatic detection if they have their
+ own caching mechanism set up.
+
+-DUSE_QT4=ON
+ Build against the deprecated Qt4 instead of the default Qt5. Note that you
+ should empty your build directory when switching between Qt versions,
+ otherwise weird things may happen.
+
+-DWITH_KDE=ON
+ Enable integration into KDE4 (with Qt4) or KDE Frameworks (with Qt5).
+
+-DWITH_BUNDLED_ICONS=ON
+ Quassel requires a number of icons that are part of the KDE/Plasma icon themes
+ Breeze and Oxygen, but are generally not supported by other themes. In order
+ to avoid missing icons, Quassel bundles the subset of icons it uses from the
+ afforementioned themes, and uses that as a fallback if the system theme does
+ not provide a required icon.
+ If it is ensured that Breeze and/or Oxygen are installed on your system (e.g.
+ through package dependencies), this option can be turned off to save less
+ than 2 MB of disk space.
+
+-DWITH_OXYGEN_ICONS=(ON|OFF)
+ Support the Oxygen icon theme. Oxygen was the default theme in KDE 4, and
+ also the bundled icon theme in Quassel before version 0.13. Since the move
+ to Qt5, the more modern Breeze icon theme is preferred, and thus Oxygen
+ is disabled by default when building against Qt5.
+
+-DWITH_WEBENGINE=ON
+ Use WebEngine for showing previews of webpages linked in the chat. Requires
+ the QtWebEngine module to be available, and increases the client's RAM usage
+ by *a lot* if enabled at runtime. Only available for Qt5. The default is ON.