+-DWITH_BREEZE_DARK=(ON|OFF)
+ Alternative icon theme to Breeze, optimized for dark desktop themes.
+ By default, WITH_BREEZE_DARK is OFF.
+
+-DWITH_OXYGEN=(ON|OFF)
+ Alternative icon theme to Breeze. Oxygen was the default theme in KDE 4, and
+ also the bundled icon theme in Quassel before version 0.13.
+ By default, WITH_OXYGEN is OFF.
+
+-DWITH_WEBENGINE=(ON|OFF)
+ 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.
+