The reason why we have a dummy, offscreen Window when we create the
GLX context is that GLX does not like it when you ask the context for
features if it's not made current to a Drawable. Maybe in the future
it will allow us to do so, but right now we have to make do with what
GLX offers us.
Instead of using g_critical() inside the create_context() implementation
of the ClutterBackendGLX we should use the passed GError, so that the
error message can bubble up to the caller.
Since we must guarantee that Cogl has a GL context to query, it is too
late to use the "dummy Window" trick from within the get_features()
virtual function implementation.
Instead, we can create a dummy Window from create_context() itself and
leave it around - basically trading a default stage with a dummy X
window.
We need to have the dummy X window around all the time so that the
GLX context can be selected and made current.
UProf is a small library that aims to help applications/libraries provide
domain specific reports about performance. It currently provides high
precision timer primitives (rdtsc on x86) and simple counters, the ability
to link statistics between optional components at runtime and makes report
generation easy.
This adds initial accounting for:
- Total mainloop time
- Painting
- Picking
- Layouting
- Idle time
The timing done by uprof is of wall clock time. It's not based on stochastic
samples we simply sample a counter at the start and end. When dealing with
the complexities of GPU drivers and with various kinds of IO this form of
profiling can be quite enlightening as it will be able to represent where
your application is blocking unlike tools such as sysprof.
To enable uprof accounting you must configure Clutter with --enable-profile
and have uprof-0.2 installed from git://git.moblin.org/uprof
If you want to see a report of statistics when Clutter applications exit you
should export CLUTTER_PROFILE_OUTPUT_REPORT=1 before running them.
Just a final word of caution; this stuff is new and the manual nature of
adding uprof instrumentation means it is prone to some errors when modifying
code. This just means that when you question strange results don't rule out
a mistake in the instrumentation. Obviously though we hope the benfits out
weigh e.g. by focusing on very key stats and by having automatic reporting.
Since asking for ARGB by default is still somewhat experimental on X11
and not every toolkit or complex widgets (like WebKit) still do not like
dealing with ARGB visuals, we should switch back to RGB by default - now
that at least we know it works.
For applications (and toolkit integration libraries) that want to enable
the ClutterStage:use-alpha property there is a new function:
void clutter_x11_set_use_argb_visual (gboolean use_argb);
which needs to be called before clutter_init().
The CLUTTER_DISABLE_ARGB_VISUAL environment variable can still be used
to force this value off at run-time.
When Clutter tries to pick an ARGB visual it tried to set the
GLX_TRANSPARENT_TYPE attribute of the FBConfig to
GLX_TRANSPARENT_RGB. However the code to do this was broken so that it
was actually trying to set the non-existant attribute number 0x8008
instead. Mesa silently ignored this so it appeared as if it was
working but the Nvidia drivers do not like it.
It appears that the TRANSPARENT_TYPE attribute is not neccessary for
getting an ARGB visual anyway and instead it is intended to support
color-key transparency. Therefore we can just remove it and get all of
the FBConfigs. Then if we need an ARGB visual we can just walk the
list to look for one with depth == 32.
The fbconfig is now stored in a single variable instead of having a
separate variable for the rgb and rgba configs because the old code
only ever retrieved one of them anyway.
When requesting the GLXFBConfig for creating the GLX context, we should
always request one that links to an ARGB visual instead of a plain RGB
one.
By using an ARGB visual we allow the ClutterStage:use-alpha property to
work as intended when running Clutter under a compositing manager.
The default behaviour of requesting an ARGB visual can be disabled by
using the:
CLUTTER_DISABLE_ARGB_VISUAL
Environment variable.
This replaces calls to the old (glx 1.2) functions glXChooseVisual,
glXCreateContext, glXMakeCurrent with the 1.3+ fbconfig varients
glXChooseFBConfig, glXCreateNewContext, glXMakeContextCurrent.
The only backend that tried to implement offscreen stages was the GLX backend
and even this has apparently be broken for some time without anyone noticing.
The property still remains and since the property already clearly states that
it may not work I don't expect anyone to notice.
This simplifies quite a bit of the GLX code which is very desireable from the
POV that we want to start migrating window system code down to Cogl and the
simpler the code is the more straight forward this work will be.
In the future when Cogl has a nicely designed API for framebuffer objects then
re-implementing offscreen stages cleanly for *all* backends should be quite
straightforward.
Instead of using ClutterActor for the base class of the Stage
implementation we should extend the StageWindow interface with
the required bits (geometry, realization) and use a simple object
class.
This require a wee bit of changes across Backend, Stage and
StageWindow, even though it's mostly re-shuffling.
First of all, StageWindow should get new virtual functions:
* geometry:
- resize()
- get_geometry()
* realization
- realize()
- unrealize()
This covers all the bits that we use from ClutterActor currently
inside the stage implementations.
The ClutterBackend::create_stage() virtual function should create
a StageWindow, and not an Actor (it should always have been; the
fact that it returned an Actor was a leak of the black magic going
on underneath). Since we never guaranteed ABI compatibility for
the Backend class, this is not a problem.
Internally to ClutterStage we can finally drop the shenanigans of
setting/unsetting actor flags on the implementation: if the realization
succeeds, for instance, we set the REALIZED flag on the Stage and
we're done.
As an initial proof of concept, the X11 and GLX stage implementations
have been ported to the New World Order(tm) and show no regressions.
Right now we just check for a NULL stage before calling glXMakeCurrent().
We can, though, get a valid stage without an implementation attached to
it while we are disposing a stage after a CLUTTER_DELETE event, since the
events processing is performed on a vblank-locked basis.
When requesting a GLX visual from the X server we should explicitly
set the GL_DEPTH_SIZE and the GL_ALPHA_SIZE bits, otherwise some
functionality might just not work, or work unreliably.
Fixes bug:
http://bugzilla.openedhand.com/show_bug.cgi?id=1723
If we manually wait for the VBLANK with:
- SGI_video_sync
- Direct usage of the DRM ioctl
Then we should call glFinish() first, or otherwise the swap-buffers
may be delayed by pending drawing and cause a tear.
http://bugzilla.openedhand.com/show_bug.cgi?id=1636
Signed-off-by: Emmanuele Bassi <ebassi@linux.intel.com>
This function should only need to be called in exceptional circumstances
since Cogl can normally determine internally when a flush is necessary.
As an optimization Cogl drawing functions may batch up primitives
internally, so if you are trying to use raw GL outside of Cogl you stand a
better chance of being successful if you ask Cogl to flush any batched
geometry before making your state changes.
cogl_flush() ensures that the underlying driver is issued all the commands
necessary to draw the batched primitives. It provides no guarantees about
when the driver will complete the rendering.
This provides no guarantees about the GL state upon returning and to avoid
confusing Cogl you should aim to restore any changes you make before
resuming use of Cogl.
If you are making state changes with the intention of affecting Cogl drawing
primitives you are 100% on your own since you stand a good chance of
conflicting with Cogl internals. For example clutter-gst which currently
uses direct GL calls to bind ARBfp programs will very likely break when Cogl
starts to use ARBfb programs internally for the material API, but for now it
can use cogl_flush() to at least ensure that the ARBfp program isn't applied
to additional primitives.
This does not provide a robust generalized solution supporting safe use of
raw GL, its use is very much discouraged.
Previously the journal was always flushed at the end of
_cogl_rectangles_with_multitexture_coords, (i.e. the end of any
cogl_rectangle* calls) but now we have broadened the potential for batching
geometry. In ideal circumstances we will only flush once per scene.
In summary the journal works like this:
When you use any of the cogl_rectangle* APIs then nothing is emitted to the
GPU at this point, we just log one or more quads into the journal. A
journal entry consists of the quad coordinates, an associated material
reference, and a modelview matrix. Ideally the journal only gets flushed
once at the end of a scene, but in fact there are things to consider that
may cause unwanted flushing, including:
- modifying materials mid-scene
This is because each quad in the journal has an associated material
reference (i.e. not copy), so if you try and modify a material that is
already referenced in the journal we force a flush first)
NOTE: For now this means you should avoid using cogl_set_source_color()
since that currently uses a single shared material. Later we
should change it to use a pool of materials that is recycled
when the journal is flushed.
- modifying any state that isn't currently logged, such as depth, fog and
backface culling enables.
The first thing that happens when flushing, is to upload all the vertex data
associated with the journal into a single VBO.
We then go through a process of splitting up the journal into batches that
have compatible state so they can be emitted to the GPU together. This is
currently broken up into 3 levels so we can stagger the state changes:
1) we break the journal up according to changes in the number of material layers
associated with logged quads. The number of layers in a material determines
the stride of the associated vertices, so we have to update our vertex
array offsets at this level. (i.e. calling gl{Vertex,Color},Pointer etc)
2) we further split batches up according to material compatability. (e.g.
materials with different textures) We flush material state at this level.
3) Finally we split batches up according to modelview changes. At this level
we update the modelview matrix and actually emit the actual draw command.
This commit is largely about putting the initial design in-place; this will be
followed by other changes that take advantage of the extended batching.
This is the another step into abstracting the backend operations
that are currently spread all across the board back into the
backend implementations where they belong.
The GL context creation, for instance, is demanded to the stage
realization which makes it a critical path for every operation
that is GL-context bound. This usually does not make any difference
since we realize the default stage, but at some point we might
start looking into avoiding the default stage realization in order
to make the Clutter startup faster.
It also makes the code maintainable because every part is self
contained and can be reworked with the minimum amount of pain.
The XVisualInfo for GL is created when a stage is being realized.
When embedding Clutter inside another toolkit we might not want to
realize a stage to extract the XVisualInfo, then set the stage
window using a foreign X Window -- which will cause a re-realization.
Instead, we should abstract as much as possible into the X11 backend.
Unfortunately, the XVisualInfo for GL is requested using GLX API; for
this reason we have to create a ClutterBackendX11 method that we
override inside the ClutterBackendGLX implementation.
This also allows us to move a little bit of complexity from out of
the stage realization, which is currently a very delicate and hard
to debug section.
The fix for bug 1138 broke multi-stage support on GLX, causing
X11 to segfault with the following stack trace:
Backtrace:
0: /usr/X11R6/bin/X(xf86SigHandler+0x7e) [0x80c91fe]
1: [0xb7eea400]
2: /usr/lib/xorg/modules/extensions//libglx.so [0xb7ae880c]
3: /usr/lib/xorg/modules/extensions//libglx.so [0xb7aec0d6]
4: /usr/X11R6/bin/X [0x8154c24]
5: /usr/X11R6/bin/X(Dispatch+0x314) [0x808de54]
6: /usr/X11R6/bin/X(main+0x4b5) [0x8074795]
7: /lib/i686/cmov/libc.so.6(__libc_start_main+0xe5) [0xb7c75775]
8: /usr/X11R6/bin/X(FontFileCompleteXLFD+0x21d) [0x8073a81]
which I can only track down to clutter_backend_glx_ensure_current()
being passed a NULL stage -- something that happens when a stage
is not correct realized. That should lead to a glXMakeCurrent(None)
and not to a segmentation fault, though.
Clutter has a set of command line options that are added to every
application by means of clutter_init() or by obtaining the Clutter
GOptionGroup and using g_option_context_parse(). Thus, every Clutter
application will automatically have an --help command line switch
showing the list of options and their description.
At the moment, Clutter does not enable localization of the help,
thus making it less than useful on non-English locales.
This patch enables the machinery to create a localization file and
load it when initializing Clutter, by means of the GLib macros and
locale.h API we already use.
Signed-off-by: Emmanuele Bassi <ebassi@linux.intel.com>
Bug 1200 - Crash with invalid DISPLAY
* clutter/clutter-main.c: Use the ClutterBackend wrapper API
instead of directly checking the class structure.
* clutter/glx/clutter-backend-glx.c: Return the correct value
in case of failure.
* clutter/x11/clutter-backend-x11.c: Bail out if XOpenDisplay()
failed.
* clutter/glx/clutter-stage-glx.c:
(clutter_stage_glx_unrealize): Move the shaders release from here...
* clutter/glx/clutter-backend-glx.c:
(clutter_backend_glx_dispose): ... to here. Shaders should be
released when the GL context is being destroyed, and that only
happens when the backend is being disposed, now that we support
multiple stages.
* clutter/clutter-backend.c:
(_clutter_backend_create_stage): Call _clutter_stage_set_window()
ourselves, thus removing yet another action that backends must
implement and might get wrong; also cuts a backend-agnostic piece
of code duplication.
* clutter/eglnative/clutter-backend-egl.c:
(clutter_backend_egl_create_stage): Update the EGL native backend.
* clutter/eglx/clutter-backend-egl.c:
(clutter_backend_egl_create_stage): Update the EGLX backend.
* clutter/fruity/clutter-backend-fruity.c:
(clutter_backend_egl_create_stage): Update the fruity backend
* clutter/glx/clutter-backend-glx.c:
(clutter_backend_glx_create_stage): Update the GLX backend.
* clutter/sdl/clutter-backend-sdl.c:
(clutter_backend_sdl_create_stage): Update the SDL backend.
* HACKING.backends: Update the ::create_stage() description.
Rework the stage wrapper/implementation relation: remove
duplicated code and all the bookkeeping from the backends into
ClutterStage whenever possible, to reduce the amount of work a
backend must do (and possibly get wrong). Thanks to Tommi
Komulainen.
* clutter/clutter-main.c:
(clutter_init_with_args), (clutter_init): Realize the default
stage after creation. The default stage is special, because we
use it in the initialization sequence. This removes the burden
from the backends and reduces the things a backend can get
wrong.
* clutter/clutter-stage.c:
(clutter_stage_show): Make sure to realize the implementation if
it hasn't been realized yet.
(clutter_stage_realize): Set the REALIZED flag and call
clutter_stage_ensure_current() if the implementation was
successfully realized.
(clutter_stage_unrealized): Call clutter_stage_ensure_current()
on unrealize.
* clutter/glx/clutter-backend-glx.c:
(clutter_backend_glx_create_stage): Do not realize the stage anymore
when creating it, and let the normal realization sequence take
place.
(clutter_backend_glx_ensure_context): Trap for X11 errors.
* clutter/glx/clutter-stage-glx.c:
(clutter_stage_glx_realize): Chain up to the X11 implementation
so that we can set up the window state (title, cursor visibility)
when we actually have a X window. Also, do not call
clutter_stage_ensure_current(), and rely on the wrapper to do
it for us. This means we can drop setting the REALIZED flag on
the wrapper.
(clutter_stage_glx_unrealize): Do not call
clutter_stage_ensure_current() ourselves, and rely on the wrapper
to do it for us.
* clutter/x11/clutter-stage-x11.c:
(set_wm_title), (set_cursor_visible): Move the WM title and
cursor visibility code inside their own functions.
(clutter_stage_x11_realize): Set the window title and whether the
cursor is visible or not after realizing the stage.
(clutter_stage_x11_set_cursor_visible),
(clutter_stage_x11_set_title): Call set_wm_title() and
set_cursor_visible().
(clutter_stage_x11_finalize): Free the title string.
* clutter/x11/clutter-stage-x11.h: Save more of the stage state,
so that we can set it even when the stage hasn't been realized
yet.
* clutter/eglnative/clutter-backend-egl.c:
(clutter_backend_egl_create_stage):
* clutter/eglnative/clutter-stage-egl.c:
(clutter_stage_egl_unrealize),
(clutter_stage_egl_realize): Update the eglnative backend.
* clutter/eglx/clutter-backend-egl.c:
(clutter_backend_egl_ensure_context),
(clutter_backend_egl_create_stage):
* clutter/eglx/clutter-stage-egl.c:
(clutter_stage_egl_unrealize),
(clutter_stage_egl_realize): Update the eglx backend.
* clutter/sdl/clutter-backend-sdl.c:
(clutter_backend_sdl_create_stage):
* clutter/sdl/clutter-stage-sdl.c:
(clutter_stage_sdl_realize): Update the sdl backend.
* clutter/fruity/clutter-backend-fruity.c:
(clutter_backend_fruity_create_stage):
* clutter/sdl/clutter-stage-fruity.c:
(clutter_stage_fruity_realize): Update the fruity backend.
* tests/test-multistage.c (on_button_press): Bail out if
clutter_stage_new() returns NULL.
* HACKING.backends: Update backend writing documentation.
Work related to #873;
* clutter/glx/clutter-backend-glx.c:
* clutter/glx/clutter-backend-glx.h:
* clutter/x11/clutter-x11-texture-pixmap.c:
* clutter/x11/clutter-x11-texture-pixmap.h:
General cleanup of texture pixmap code, adding;
- Pixmap dimentions and depth now auto probed, read only props.
- More X safety traps
- Add support for optionally tracking damage and automatically
updating texture.
* clutter/glx/clutter-glx-texture-pixmap.c:
* clutter/glx/clutter-glx-texture-pixmap.h:
General cleanup and some safety additions. Needs more work so
'proper' subclass - dependent on new COGL.
* clutter/x11/clutter-backend-x11.c: (clutter_x11_remove_filter):
Invert g_return_if check.
* configure.ac:
Pull in XComposite and XDamage (at least for now)
* tests/Makefile.am:
* tests/test-pixmap.c:
Add a modified test from Johan for above.
* clutter/eglx/clutter-backend-egl.c:
(clutter_backend_egl_ensure_context): Sync up with the GLX
backend.
(clutter_backend_egl_create_stage): Dumb compilation fix.
* clutter/glx/clutter-backend-glx.c:
(clutter_backend_glx_create_stage): Unref the stage if we are
erroring out.
* clutter/clutter-backend.c: Add more debug messages
* clutter/clutter-stage.h:
* clutter/clutter-stage.c:
(clutter_stage_is_default): Add a function to check if the
stage is the default one.
* clutter/glx/clutter-backend-glx.c:
* clutter/glx/clutter-stage-glx.c:
* clutter/x11/clutter-stage-x11.c: Keep the stage wrapper
and implementation flags in sync, to ensure that the GL
context is always set.
Bug #864 - Allow instantiating and subclassing of ClutterStage
* clutter/Makefile.am: Add clutter-stage-window.[ch]
* clutter/clutter-stage-manager.c:
(_clutter_stage_manager_remove_stage): Do not warn if removing
a stage we don't manage, as we might be invoked multiple times
during a ClutterState dispose sequence.
* clutter/clutter-actor.c:
* clutter/clutter-backend.[ch]:
* clutter/clutter-main.c:
* clutter/clutter-private.h:
* clutter/clutter-stage.[ch]: Make ClutterStage a proxy actor,
with a private actor implementing the ClutterStageWindow
interface for handling the per-backend realization, painting
and unrealization, plus all the windowing system abstraction.
* clutter/x11/clutter-event-x11.c:
* clutter/x11/clutter-stage-x11.[ch]: Port the X11 backend
to the new backend and stage API and semantics.
* clutter/glx/clutter-backend-glx.c:
* clutter/glx/clutter-stage-glx.c: Port the GLX backend to
the new backend and stage API and semantics.
* clutter/eglx/clutter-backend-egl.[ch]:
* clutter/eglx/clutter-stage-egl.[ch]: Port the EGLX backend
to the new backend and stage API and semantics (untested).
* tests/test-multistage.c (on_button_press): Rename
clutter_stage_create_new() to clutter_stage_new().
* clutter/glx/clutter-backend-glx.c:
(clutter_backend_glx_get_features): Assert if we don't have a
GL context here or if it's not matched to a drawable. Asserting
might seem too drastic, but if we don't have a valid GL context
here then Clutter will segfault anyway, and I'll take an assert()
over a hard to read, deep in GLX guts backtrace any day (and
twice on a monday).
* clutter/x11/clutter-backend-x11.c:
(clutter_backend_x11_get_features): No need for a variable here.
* clutter/clutter-backend.c:
* clutter/glx/clutter-backend-glx.c:
* clutter/glx/clutter-stage-glx.c:
Allow NULL to be passed to _clutter_backend_ensure_context
which essentially clears GL context. This is hooked into stage
unrealisation. Isn't yet quite bulletproof.
Fixes issues with gtk-embed crasher (thanks to Neil).
* README:
Add notes on new multistage feature.
* clutter/clutter-stage-manager.c:
Dont ref contained stages.
* clutter/clutter-stage.c:
Automatically remove stage from stage manager on finalisation.
Cleans up warnings when a stage is destroyed.
* clutter/clutter-backend.h:
* clutter/glx/clutter-backend-glx.c:
Minor formatting cleanups.
* clutter/glx/clutter-stage-glx.c:
* configure.ac:
* clutter/clutter-version.h.in:
Add a general CLUTTER_STAGE_TYPE define, should be useful for
evntual stage subclassing and creating with g_object_new()
* clutter/Makefile.am:
* clutter/eglx/Makefile.am:
* clutter/eglx/clutter-backend-egl.c:
* clutter/eglx/clutter-backend-egl.h:
* clutter/eglx/clutter-eglx.h:
* clutter/eglx/clutter-event-egl.c:
* clutter/eglx/clutter-stage-egl.c:
* clutter/eglx/clutter-stage-egl.h:
* clutter/glx/Makefile.am:
* clutter/glx/clutter-backend-glx.c:
* clutter/glx/clutter-backend-glx.h:
* clutter/glx/clutter-event-glx.c:
* clutter/glx/clutter-glx.h:
* clutter/glx/clutter-stage-glx.c:
* clutter/glx/clutter-stage-glx.h:
* clutter/x11/Makefile.am:
* clutter/x11/clutter-backend-x11-private.h:
* clutter/x11/clutter-backend-x11.c:
* clutter/x11/clutter-backend-x11.h:
* clutter/x11/clutter-event-x11.c:
* clutter/x11/clutter-stage-x11.c:
* clutter/x11/clutter-stage-x11.h:
* clutter/x11/clutter-x11.h:
Create a new X11 backend class of which EGL and GLX 'real' backends
then subclass. Effectively shares all X11 code between both backends
avoids code duplication and brings many missing features to EGL X
backend. Requires some cleanup and testing. (#518)
* clutter/cogl/gles/cogl.c: (cogl_color):
Add define to use color4ub only if configure finds it.
If not fall back to old code.
* configure.ac:
Drop support for vincent checks.
Drop sdles backend.
Specifically check for color4ub call.
* clutter/clutter-actor.c:
* clutter/clutter-event.h:
* clutter/clutter-main.c:
* clutter/clutter-stage.c:
* clutter/clutter-stage.h:
* clutter/glx/clutter-backend-glx.c:
* clutter/glx/clutter-backend-glx.h:
* clutter/glx/clutter-event-glx.c:
* clutter/glx/clutter-stage-glx.c:
* clutter/glx/clutter-stage-glx.h:
Add initial support for stage state events.
Fix fullscreening for an already mapped stage.
* tests/test-events.c:
Print out info from the above. Blue button now toggles
fullscreen.
* clutter/clutter-effect.c:
* clutter/clutter-effect.h:
Add a setting for templates to ref or clone underlying
timelines. (As to improve sync issues like those in foofone)
* tests/test-timeline.c:
Also add completed signals.
* clutter/cogl/gles/cogl.c: (cogl_texture_image_2d):
* configure.ac:
Forward port from stable branch. RGB Image fixes gles
and check for lower case libgles_cm.
* clutter/clutter-actor.c:
* clutter/clutter-actor.h:
* clutter/clutter-event.c:
* clutter/clutter-event.h:
* clutter/clutter-main.c:
* clutter/clutter-main.h:
* clutter/clutter-private.h:
* clutter/clutter-stage.c:
* clutter/clutter-stage.h:
* clutter/clutter-types.h:
Initial implementation of actors emmitting event signals (423);
- Actors set_reactive() to receive mouse events.
(call clutter_enable_motion_events() for per action motion events)
- clutter_stage_set_key_focus () to direct key events.
- Events bubble up to parents (ending at stage)
(original source identified by clutter_event_get_source())
TODO:
- enter/leave notifys for actors.
- stage specific events - fullscreen
- grabs
* tests/test-events.c:
Extend a little to use new API
* clutter/cogl/gl/cogl.c:
* clutter/glx/clutter-backend-glx.c:
Move get_proc_address into cogl and out of backend.
(shaders will need it)
* clutter/clutter-group.c: (clutter_group_real_lower):
Fix a minor compile warning.
* TODO:
Sync up.
* clutter/clutter-backend.[ch]: Add clutter_backend_set_resolution()
and clutter_backend_get_resolution(); backends should use the former
to set the resolution of the display when initialising, while actors
should use the latter when sizing themselves depending on the
resolution or the font size.
* clutter/glx/clutter-backend-glx.c: Set the resolution as 96 dpi
as a default and query the X server when opening the display.
* clutter/clutter-entry.c: Drop the hardcoded dpi value and use
clutter_backend_get_resolution() to compute the default size.
* clutter/clutter-feature.h:
Add new stage feature flags and document.
* clutter/eglnative/clutter-backend-egl.c:
* clutter/eglx/clutter-backend-egl.c:
* clutter/sdl/clutter-backend-sdl.c:
Set new feature flags.
* clutter/glx/clutter-backend-glx.c:
* clutter/glx/clutter-stage-glx.c:
* clutter/clutter-stage.c:
* clutter/clutter-stage.h:
Add a 'user_resizeable' setting to the backend and implement
for glx backend.
