22.04 MATE Tweak window manager selection not finding picom config file

guyr · 24 September 2023 09:32

I'm tinkering trying to get transparent window title bars as in Windows Aero. I discovered picom can provide this, so following the picom man page, I copied /usr/share/doc/picom/examples/picom.sample.conf to ~/.config/picom.conf. i then used MATE Tweak to change the window manager to Marco (picom: Xrender), but none of the visual effects appeared. I tried the other picom options - GLX and Hybrid - and again, no visual effects appeared. So I then opened up a terminal window, and ran simply "picom", and then the visual effects appeared. So, from a command prompt at least, picom appears to be able to find the config file in the standard location.

So, why when I change the window manager from within MATE Tweak is the config file not taking effect?

guyr · 24 November 2023 07:36

I believe I've figured this out. MATE Tweak is using file /usr/bin/marco-xrender to configure a picom xrender environment. I saved a version of this file in my ~/bin directory, and MATE Tweak also found that version before finding /usr/bin/marco-xrender. I discovered that by trial and error; changes I made to /usr/bin/marco-xrender were not taking effect while I had ~/bin/marco-xrender. Once I also made the same changes to the version in my home directory, then MATE Tweak showed all the settings. This is actually a good thing, once we realize this is what is happening; it allows the user to make changes to his/her own tweaked environment without having to change it for everyone else.

Some additional documentation for MATE Tweak would be helpful. Especially confusing is that if MATE Tweak is installed, it apparently takes precedent over the default picom configuration mechanism.

ironfoot · 24 November 2023 22:05

Hi, @guyr!

MATE Tweak is looking for these marco+compositor scripts in your $PATH using self-written find_on_path function. You may want to check the following code pieces.

github.com

ubuntu-mate/mate-tweak/blob/master/mate-tweak#L1173

      
        
                try:
                    ldd = subprocess.Popen('ldd /usr/bin/marco', shell=True, stdout=subprocess.PIPE)
                    for line in ldd.stdout:
                        if "libXpresent" in str(line):
                            compositor = "Xpresent"
                            break
                except:
                    pass
                wms.append([_("Marco (built-in: "+compositor+")"), 'marco'])
            if self.marco_picom_capable and not self.software_rasterizer:
                if self.find_on_path('marco-xrender'):
                    wms.append([_("Marco (picom: Xrender)"), 'marco-xrender'])
                if self.find_on_path('marco-glx'):
                    wms.append([_("Marco (picom: GLX)"), 'marco-glx'])
                if self.find_on_path('marco-xr_glx_hybrid'):
                    wms.append([_("Marco (picom: Hybrid)"), 'marco-xr_glx_hybrid'])
            if self.compiz_capable:
                wms.append([_("Compiz (Advanced GPU accelerated desktop effects)"), 'compiz'])
            
            
if self.current_wm == 'Unknown':
                self.builder.get_object("label_unknown_wm").set_markup('<span size="small" foreground="#cc0000">' + _("You are currently using an unknown and unsupported window manager. Thus we cannot guarantee that changes made here will be effective.") + '</span>')

github.com

ubuntu-mate/mate-tweak/blob/master/mate-tweak#L274

      
        
                    except psutil.NoSuchProcess:
                        pass
                    else:
                        if name == proc['name'] and uid == proc['uids'].real:
                            try:
                                target = psutil.Process(proc['pid'])
                                target.terminate()
                            except psutil.NoSuchProcess:
                                pass
            
            
def find_on_path(self, command):
                """Is command on the executable search path?"""
                if 'PATH' not in os.environ:
                    return False
                path = os.environ['PATH']
                for element in path.split(os.pathsep):
                    if not element:
                        continue
                    filename = os.path.join(element, command)
                    if os.path.isfile(filename) and os.access(filename, os.X_OK):
                        return True

So, the results of your experiments really depend on the order of elements in your $PATH.
Update: the find_on_path function is only used to check the available options, when the scripts are indeed launched, the $PATH is searched again implicitly using system functions.

The script explicitly checks for a config file named ~/.config/marco-picom.conf, this name is not default.

github.com

ubuntu-mate/mate-tweak/blob/master/marco-wrapper#L43

      
        
                    VSYNC="--no-vsync"
                fi
            fi
            
            
killall --user "${UNAME}" compton 2>/dev/null
            killall --user "${UNAME}" picom 2>/dev/null
            
            
if [ -n "${COMP}" ]; then
                # Allow users to override the defaults by creating their own config
                # for this wrapper.
                if [ -f "${HOME}/.config/${WM}-${COMP}.conf" ]; then
                    ${COMP} \
                        --daemon \
                        --config "${HOME}/.config/${WM}-${COMP}.conf"
                else
                    ${COMP} \
                        --daemon \
                        --config /dev/null \
                        --backend ${BACKEND} ${VSYNC} \
                        --detect-rounded-corners \
                        --detect-client-leader \

If this config file is missing, picom is started without a config file with the parameters specified in the script.

github.com

ubuntu-mate/mate-tweak/blob/master/marco-wrapper#L50

      
        
            if [ -n "${COMP}" ]; then
                # Allow users to override the defaults by creating their own config
                # for this wrapper.
                if [ -f "${HOME}/.config/${WM}-${COMP}.conf" ]; then
                    ${COMP} \
                        --daemon \
                        --config "${HOME}/.config/${WM}-${COMP}.conf"
                else
                    ${COMP} \
                        --daemon \
                        --config /dev/null \
                        --backend ${BACKEND} ${VSYNC} \
                        --detect-rounded-corners \
                        --detect-client-leader \
                        --detect-transient \
                        --detect-client-opacity \
                        --glx-no-stencil \
                        --no-use-damage \
                        --mark-wmwin-focused \
                        --mark-ovredir-focused \
                        --shadow \

I believe the intended way to make changes for a specific user is to use a config file in their home directory.

guyr · 25 November 2023 09:29

@ironfoot, thank you for the extensive research. I didn't get home until late tonight, so I need some time to digest. I started out using a picom.conf script in my ~/.config directory, but wasn't getting the same results produced from the marco-xrender script. That's when I shifted gears to modifying marco-xrender. I'll try again with marco-picom.conf as you suggest.

I'll post again if I have additional questions or comments. Have a nice weekend.

[EDIT] And that worked. For the sake of anyone else who may find this via search, command line picom.exe looks for ~/.config/picom.conf, while MATE Tweak looks for ~/.config/marco-picom.conf.