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Clutter automatically checks environment variables during its initialization. These environment variables are meant as debug tools, overrides for default behaviours or to address known hardware issues:
| CLUTTER_BACKEND | Changes the windowing system backend used by Clutter. The allowed values for this environment variable depend on the configuration options used when compiling Clutter. The available values are: 
 All of the above options except for the  | 
| CLUTTER_INPUT_BACKEND | Changes the input backend used by Clutter. The allowed values for this environment variable depend on the configuration options used when compiling Clutter. The available values are: 
 This environment variable is only useful for setting the input
            backend when using a windowing system backend that does not have an
            input API, like the  | 
| CLUTTER_DRIVER | Changes the GL driver used when initializing Clutter. The allowed values for this environment variable are: 
 The special '*' value can be used to ask Clutter to use the default list of drivers, e.g. 'CLUTTER_DRIVER=gles2,*' will ask Clutter to try the GLES 2.0 driver first, and then fall back to the default list of Cogl drivers. | 
| CLUTTER_SCALE | Forces the window scaling factor to that value inside Clutter instead of relying on what backends detect. | 
| CLUTTER_TEXT_DIRECTION | Forces the text direction of every Pango layout inside Clutter. Valid values are: ltr or rtl | 
| CLUTTER_SHOW_FPS | Prints out the frames per second achieved by Clutter. | 
| CLUTTER_DEFAULT_FPS | Sets the default framerate. | 
| CLUTTER_DISABLE_MIPMAPPED_TEXT | Disables mipmapping when rendering text. | 
| CLUTTER_FUZZY_PICK | Enables "fuzzy picking". | 
| CLUTTER_DEBUG | Enables debugging modes for Clutter; debugging modes are used to print debugging messages on the console. Clutter must be compiled with the --enable-debug configuration switch for these messages to be printed out. Multiple debugging modes can be enabled by separating them using a colon (":") or a comma (","). | 
| CLUTTER_PAINT | Enables paint debugging modes for Clutter; the modes change the way Clutter paints a scene and are useful for debugging the behaviour of the paint cycle. | 
| CLUTTER_ENABLE_DIAGNOSTIC | When set to 1, enables diagnostic messages for run-time
            deprecations, similarly to  | 
On the GLX backend there is also:
| CLUTTER_VBLANK | Selects the sync-to-vblank mode to be used. Valid values are: none, dri or glx | 
Similarly to the environment variables, Clutter also installs command line switches that are parsed during initialization:
| --clutter-show-fps | Equivalent of CLUTTER_SHOW_FPS. Prints the current rendering speed in frames per second. | 
| --clutter-default-fps=FPS | Equivalent of CLUTTER_DEFAULT_FPS. Sets the default framerate. | 
| --clutter-text-direction=DIRECTION | Equivalent of CLUTTER_TEXT_DIRECTION. Sets the direction for the text. | 
| --clutter-disable-mipmapped-text | Equivalent of CLUTTER_DISABLE_MIPMAPPED_TEXT. Disables mipmapping when rendering text. | 
| --clutter-use-fuzzy-picking | Equivalent of CLUTTER_FUZZY_PICK. Enables "fuzzy" picking. | 
| --clutter-debug=FLAGS | Equivalent of CLUTTER_DEBUG. Sets FLAGS as the Clutter debugging flags. | 
| --clutter-no-debug=FLAGS | Unsets FLAGS from the Clutter debugging flags. | 
| --cogl-debug=FLAGS | Equivalent of COGL_DEBUG. Sets FLAGS as the Cogl debugging flags. | 
| --cogl-no-debug=FLAGS | Unsets FLAGS from the Cogl debugging flags. | 
| --clutter-enable-accessibility | Enables accessibility support. | 
The X11 backends also have the following command line options:
| --display=DISPLAY | Sets the X11 display to use. | 
| --screen=SCREEN | Sets the X11 screen number to use. | 
| --synch | Make X11 calls synchronous. | 
The GLX backend also has the following command line option:
| --vblank=METHOD | Equivalent of CLUTTER_VBLANK. Sets the sync-to-vblank method to be used. | 
The debugging flags can be used for the CLUTTER_DEBUG environment variable and the --clutter-debug command line switch. Multiple flags can be separated by a colon (:) or a comma (,).
| actor | Generic actor-related notes | 
| animation | ClutterAnimation notes | 
| backend | Backend-related notes, including initialization of the backend features and GL context creation | 
| event | Event handling notes | 
| layout | ClutterLayoutManager notes | 
| misc | Miscellaneous notes | 
| scheduler | Notes related to timelines and the master clock | 
| script | Notes related to ClutterScript | 
It is possible to get all the debugging notes using the special "all" flag.
Clutter will look for files named settings.ini
      located in the /etc/clutter-1.0 and
      $XDG_CONFIG_HOME/clutter-1.0 directories. These files
      must be valid key files (see GKeyFile in the GLib documentation) and may
      have three sections:
| Environment | The keys in this section map the environment variables honoured by Clutter. | 
| Debug | The keys in this section related to the debugging notes that Clutter exposes when compiled with debugging support; similarly to the environment variables and command line arguments related to the debugging notes, Clutter must be compiled with support for these notes in order to use them. | 
| Settings | The keys in this section strictly map to the GObject
          properties exposed by the ClutterSettings type; if Clutter is running
          on an X11 platform, the XSettings manager will take precedence over the
          values specified in the  | 
| Backends | A string value, equivalent to setting
             | 
| Drivers | A string value, equivalent to setting
             | 
| ShowFps | A boolean value, equivalent to setting
             | 
| DisableMipmappedText | A boolean value, equivalent to setting
             | 
| UseFuzzyPicking | A boolean value, equivalent to setting
             | 
| EnableAccessibility | A boolean value, equivalent to setting
             | 
| SyncToVblank | A boolean value, equivalent to setting
             | 
| DefaultFps | An integer value, equivalent to setting
             | 
| TextDirection | A string value, equivalent to setting
             | 
| Debug | A string containing the debugging flags, in the same
            format that should be used with the  | 
| PaintDebug | A string containing the paint debugging flags, in the same
            format that should be used with the  | 
| PickDebug | A string containing the pick debugging flags, in the same
            format that should be used with the  |