I think this is a bug in the KWin detection system.

Try checking "disable functionality tests" in the advanced tab.

Are you using the "nvidia" closed source driver?
Be aware that this is a fairly old GPU (it's actually a relabled GF2) and long ago nvidia did not support GLX + Composite, you had to set

Option "AllowGLXWithComposite" "true"

in the Device section of xorg.conf (and this would not mean it would actually be usable, prepare for crashes)

I am using the current closed source driver.
As for GLX support... if the specs state that the video card is "fully compliant with OpenGL 1.3 API, should it not support KDE4 compositing?
I realize that I do not have the line: "Option "AllowGLXWithComposite" "true"
 (so I will reboot and see if this makes any difference)


(In reply to comment #2)
> Try checking "disable functionality tests" in the advanced tab.
> 
> Are you using the "nvidia" closed source driver?
> Be aware that this is a fairly old GPU (it's actually a relabled GF2) and long
> ago nvidia did not support GLX + Composite, you had to set
> 
> Option "AllowGLXWithComposite" "true"
> 
> in the Device section of xorg.conf (and this would not mean it would actually
> be usable, prepare for crashes)

(In reply to comment #2)
> Be aware that this is a fairly old GPU (it's actually a relabled GF2) and long
> ago nvidia did not support GLX + Composite, you had to set
> 
> Option "AllowGLXWithComposite" "true"

After including the above option in xorg I cannot use compositing at all (even Xrender).
As well, I used a system-benchmarking app for analyzing my video cards specs, and it shows that it does compositing and GLX.  (It only shows them as separate features... must compositing + GLX be shown as a combined extension?)

So as far as I'm concerned this is still a bug unless there is someone else who can use OpenGL on KDE4 with a GeForce4 video card.

A geforce4 card is quite old and it's unfortunately possible that Compositing is unsupported in the legacy drivers.

The geforce4 cards are old, but with the legacy driver they do support Compositing. I use the legacy 96.43 driver on an GeForce4 MX intergrated GPU, and have compositing working(KDE 4.3).

But as as I recall, setting up the xorg config required some tries. I do not remember how I got it working on my xorg version, but you may get some hints from this. From my xorg.conf I have the following:

In section "Screeen"
    Option         "AllowGLXWithComposite" "true"
    Option         "AddARGBGLXVisuals" "true"
    Option         "RenderAccel" "true"

Section "Extensions"
    Option         "Composite" "on"
EndSection

Section "Module"
    Load           "dbe"
    Load           "freetype"
    Load           "extmod"  
    Load           "glx"     
EndSection

kwin activates compositing only if the driver version is at least 173.14.12.

It is possible that Compositing support was broken for the legacy driver in recent versions of X Server. I don't know if NVIDIA changes their legacy drivers to work with recent versions of X, but I would not be surprised if they don't (Ati dropped support for legacy cards).

Kwin should also have enabled compositing for some legacy drivers, at least the 96.43 as it works quite well.

For me the legacy driver has worked at least since 96.43.11(09.03.2009), and it worked before support for my card got moved to a legacy driver(For the releases in-between I'm not sure).

Up to now NVIDIA have upgraded their legacy drivers for newer X servers and Linux kernels.
- Version: 96.43.11
  Improved compatibility with recent Linux 2.6 kernels.
  Added support for X.Org server 1.5 and 1.6.
- Version: 96.43.13
  Improved compatibility with recent Linux kernels.
- Version: 96.43.14 
  Added support for X.Org xserver 1.7.

But that is in any case not important, if the driver don't support newer X servers the question of compositing becomes irrelevant. As the driver would not work in any case;-)

one more thing, as this is an NV17 or NV18 chip, better check

   glxinfo -l | grep -Ei 'max_texture_si|dim'

(i think GL_MAX_TEXTURE_SIZE was 512, what would make it unusable)

this is the output:
    GL_MAX_TEXTURE_SIZE = 2048
    GL_MAX_VIEWPORT_DIMS = 4096, 4096
so it appears that this is not the issue.

(In reply to comment #9)
> one more thing, as this is an NV17 or NV18 chip, better check
> 
>    glxinfo -l | grep -Ei 'max_texture_si|dim'
> 
> (i think GL_MAX_TEXTURE_SIZE was 512, what would make it unusable)

(In reply to comment #6)
> The geforce4 cards are old, but with the legacy driver they do support
> Compositing. I use the legacy 96.43 driver on an GeForce4 MX intergrated GPU,
> and have compositing working(KDE 4.3).
> 
> But as as I recall, setting up the xorg config required some tries. I do not
> remember how I got it working on my xorg version, but you may get some hints
> from this. From my xorg.conf I have the following:
> 
> In section "Screeen"
>     Option         "AllowGLXWithComposite" "true"
>     Option         "AddARGBGLXVisuals" "true"
>     Option         "RenderAccel" "true"
> 
> Section "Extensions"
>     Option         "Composite" "on"
> EndSection
> 
> Section "Module"
>     Load           "dbe"
>     Load           "freetype"
>     Load           "extmod"  
>     Load           "glx"     
> EndSection

SUCCESS!!  Thanks Knuts and all for your suggestions...  I still have some tweaking to do, as I don't know if all these settings are needed (so it will be trial and error).  I would welcome any suggestions on how to modify the below xorg file:
-----------------------------
# nvidia-settings: X configuration file generated by nvidia-settings
# nvidia-settings:  version 1.0  (buildmeister@builder62)  Mon Nov  9 06:18:37 PST 2009

Section "ServerLayout"
    Identifier     "Layout0"
    Screen      0  "Screen0" 0 0
    InputDevice    "Keyboard0" "CoreKeyboard"
    InputDevice    "Mouse0" "CorePointer"
EndSection

Section "Files"
EndSection

Section "ServerFlags"
    Option         "Xinerama" "0"
EndSection

Section "Module"
    Load           "dbe"
    Load           "extmod"
    Load           "type1"
    Load           "freetype"
    Load           "glx"
EndSection

Section "InputDevice"
    # generated from default
    Identifier     "Mouse0"
    Driver         "mouse"
    Option         "Protocol" "auto"
    Option         "Device" "/dev/psaux"
    Option         "Emulate3Buttons" "no"
    Option         "ZAxisMapping" "4 5"
EndSection

Section "InputDevice"
    # generated from default
    Identifier     "Keyboard0"
    Driver         "kbd"
EndSection

Section "Monitor"
    # HorizSync source: edid, VertRefresh source: edid
    Identifier     "Monitor0"
    VendorName     "Unknown"
    ModelName      "Acer X193W"
    HorizSync       30.0 - 83.0
    VertRefresh     55.0 - 75.0
    Option         "DPMS"
EndSection

Section "Device"
    Identifier     "Videocard0"
    Driver         "nvidia"
    VendorName     "NVIDIA Corporation"
    BoardName      "GeForce4 MX 4000"
    Option         "UseEDIDFreqs" "false"
    Option         "NoEDIDModes" "true"
EndSection

Section "Screen"
    Identifier     "Screen0"
    Device         "Videocard0"
    Monitor        "Monitor0"
    DefaultDepth    24
    Option         "metamodes" "1440x900_75 +0+0; nvidia-auto-select +0+0"
    Option         "AllowGLXWithComposite" "true"
    Option         "AddARGBGLXVisuals" "true"
    Option         "RenderAccel" "true"
    SubSection     "Display"
        Depth       24
        Modes      "1600x1200" "1280x1024" "1024x768" "800x600" "640x480"
    EndSubSection
EndSection

Section "Extensions"
    Option         "Composite" "on"
EndSection