i want to share some of my solutions in fixing desktop environmet into usable state in parabola. so im created this wiki draft (it still in raw plain though).
before that i need to polish this wiki because my english is not that pro and i need others to confirm that this wiki guide using the right method and wont
result into bad state, also i want to know if other user experiencing the same error. anyone are welcomed to audit, echance, adopt, and give suggestions.

my backgrounds:
-device used: asus u36sd laptop (some error listed here might not occured in other devices)
-observed in: gnome 3.32.2 latest (if i recall this plague started in gnome 3.28 and up)
-tested on: parabola x86_64 desktop with systemd (stock and testing repository)

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parabola desktop environment related troubleshooting
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some desktop environment are tightly integrated or depends on lots of components. in restricted free only environment like parabola, those nonfree packages might
be missing, causing them to misbehave or dont work out properly. an non free component that has been purged out by parabola also my cause some problem for hardware and software who depend on them. if you are experience some of those, try to find some solutions below, if the error continues please consult into parabola community channel, also if you found new error or solutions please share them there.

1 cannot login into gnome desktop
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1.1 problem:
1) successfull login, but gnome giving a fullscreen error windows forcing you to logout (this is called failwhale)
2) successfull login, but with blank screen and mouse cursor
3) unsuccessfull login, kicked back to login screen

1.2 causes:
1) an required gnome component cant load properly
2) an required gnome packages didnt installed correctly
3) some required packages ignored from install because they re blacklisted

1.3 solutions:
1) open your terminal and use your favorite text editor and change the required gnome component to be minimum as possible:
$ nano /usr/share/gnome-session/sessions/gnome.session
comment out the line that says this word below (usually you can find it on the bottom end)

RequiredComponents=org.gnome.Shell;org.gnome.SettingsDaemon.A11ySettings;org.gnome.SettingsDaemon.Clipboard;org.gnome.SettingsDaemon.Color;org.gnome.SettingsDaemon.Datetime;org.gnome.SettingsDaemon.Housekeeping;org.gnome.SettingsDaemon.Keyboard;org.gnome.SettingsDaemon.MediaKeys;org.gnome.SettingsDaemon.Mouse;org.gnome.SettingsDaemon.Power;org.gnome.SettingsDaemon.PrintNotifications;org.gnome.SettingsDaemon.Rfkill;org.gnome.SettingsDaemon.ScreensaverProxy;org.gnome.SettingsDaemon.Sharing;org.gnome.SettingsDaemon.Smartcard;org.gnome.SettingsDaemon.Sound;org.gnome.SettingsDaemon.Wacom;org.gnome.SettingsDaemon.XSettings;

to be like this

#RequiredComponents=org.gnome.Shell;org.gnome.SettingsDaemon.A11ySettings;org.gnome.SettingsDaemon.Clipboard;org.gnome.SettingsDaemon.Color;org.gnome.SettingsDaemon.Datetime;org.gnome.SettingsDaemon.Housekeeping;org.gnome.SettingsDaemon.Keyboard;org.gnome.SettingsDaemon.MediaKeys;org.gnome.SettingsDaemon.Mouse;org.gnome.SettingsDaemon.Power;org.gnome.SettingsDaemon.PrintNotifications;org.gnome.SettingsDaemon.Rfkill;org.gnome.SettingsDaemon.ScreensaverProxy;org.gnome.SettingsDaemon.Sharing;org.gnome.SettingsDaemon.Smartcard;org.gnome.SettingsDaemon.Sound;org.gnome.SettingsDaemon.Wacom;org.gnome.SettingsDaemon.XSettings;

RequiredComponents=org.gnome.Shell

save and exit 

2) assumed that you have a working xorg installation:
ensure the gnome packages are installed correctly and up to date
$ sudo pacman -Syu
$ sudo pacman -S gnome-session gnome-shell gnome-desktop
if you dont see any error but the problem continues try
$ sudo pacman -S gnome

3) (sadly) the only solutions known is to install nonprivacy geoclue package and uninstall your-privacy (if you had installed it)
$ sudo pacman -R your-privacy
$ sudo pacman -S geoclue
note: interesting fact is if you install the your-privacy package or remove geoclue (whose conflit with your-privacy package) gnome will broke, kicked you back to login screen immediately after login. it s still a mystery what relations and why this thing can happen (hope the time will come for someone who can fix this)

2 GDM login manager cant start
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2.1 problem:
black screen with terminal cursor blinking (usually seen on top right edge of your monitor)

2.2 causes:
(sadly) because you install your-privacy package or remove nonprivacy geoclue package (the same cases as gnome desktop)

2.3 solutions:
(sadly) remove your privacy (if any) and install geoclue (the same cases as gnome desktop)
$ sudo pacman -R your-privacy
& sudo pacman -S geoclue
note: its seem that geolocation awareness is integrated very tight in latest release, maybe some low level internal fix is needed instead

3 cannot login into budgie desktop
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3.1 problem:
login into budgie desktop gets kicked back to login screen

3.2 causes:
an required gnome component dependent by budgie desktop cant load properly (the same cases as gnome desktop)

3.3 solutions:
1) open your terminal and use your favorite text editor and change the required gnome component to be minimum as possible:
$ nano /usr/share/gnome-session/sessions/budgie-desktop.session

comment out the line that says this word below (usually you can find it on the bottom end)

RequiredComponents=budgie-wm;budgie-daemon;budgie-panel;budgie-polkit;org.gnome.SettingsDaemon.A11ySettings;org.gnome.SettingsDaemon.Clipboard;org.gnome.SettingsDaemon.Color;org.gnome.SettingsDaemon.Datetime;org.gnome.SettingsDaemon.Housekeeping;org.gnome.SettingsDaemon.Keyboard;org.gnome.SettingsDaemon.MediaKeys;org.gnome.SettingsDaemon.Mouse;org.gnome.SettingsDaemon.Power;org.gnome.SettingsDaemon.PrintNotifications;org.gnome.SettingsDaemon.Rfkill;org.gnome.SettingsDaemon.ScreensaverProxy;org.gnome.SettingsDaemon.Sharing;org.gnome.SettingsDaemon.Smartcard;org.gnome.SettingsDaemon.Sound;org.gnome.SettingsDaemon.Wacom;org.gnome.SettingsDaemon.XSettings;

to be like this

#RequiredComponents=budgie-wm;budgie-daemon;budgie-panel;budgie-polkit;org.gnome.SettingsDaemon.A11ySettings;org.gnome.SettingsDaemon.Clipboard;org.gnome.SettingsDaemon.Color;org.gnome.SettingsDaemon.Datetime;org.gnome.SettingsDaemon.Housekeeping;org.gnome.SettingsDaemon.Keyboard;org.gnome.SettingsDaemon.MediaKeys;org.gnome.SettingsDaemon.Mouse;org.gnome.SettingsDaemon.Power;org.gnome.SettingsDaemon.PrintNotifications;org.gnome.SettingsDaemon.Rfkill;org.gnome.SettingsDaemon.ScreensaverProxy;org.gnome.SettingsDaemon.Sharing;org.gnome.SettingsDaemon.Smartcard;org.gnome.SettingsDaemon.Sound;org.gnome.SettingsDaemon.Wacom;org.gnome.SettingsDaemon.XSettings;

RequiredComponents=budgie-wm;budgie-daemon;budgie-panel;budgie-polkit;

save and exit
note: interesting fact that installing your-privacy wouldnt break budgie but there still a bug that if you logout and login into budgie the 2nd time, you get only blank desktop with cursor, so think out before you log out

4 missing network manager, battery icon and some system tray on some desktop environment
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4.1 problem:
1) network manager tray not show up or disabled on the panel
2) network manager wont run
3) some other system tray not show up on some desktop environment  eg. mate, xfce, lxde etc..

4.2 causes:
1) you still dont enable and run the network manager service yet
2) check out if you using a some nonfree network card model that isnt supported by free firmware driver yet
3) its probably because you dont install the package completly or doesnt add the panel applet yet

4.3 solutions:
1) run the network manager service
for systemd
$ sudo systemctl enable NetworkManager
$ sudo systemctl start NetworkManager
for openrc
$ rc-update add NetworkManager default
$ rc-service NetworkManager start
logout and login back to apply the changes

2) find out and use free external network device like ethernet cable, usb dongle, modem etc..

3) install the complete package group set (the name can be various) example:
$ sudo pacman -S mate mate-extra xfce4 xfc4-goodies (etc..)
search and install a standalone trayer applets (lightweight desktop eg. lxde, openbox, i3 generaly uses a standalone trayer) example:
$ sudo pacman -S volwheel cbatticon alltray (etc..)
if everything done you still need to add the apllet to the panel yourself usually by right clicking on the panel and bring up the panel menu window

5 screen brightness get reseted every login time
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5.1 problem:
cant save screen brightness setting, every new login the screen brightness are set back to 100%

5.2 causes:
your screen brightness backlight controller might not working properly (possibly non free)

5.3 solutions:
install a standalone backlight controller program (recommended: light)
$ sudo pacman -S light (usage example $ light -S 30 : set your screen brightness to 30)
add them as an startup service eg. place it on xinit scripts, bashrc, use your desktop control panel settings etc..

6 kde dolphin scrolls view too fast
-----------------------------------
6.1 problem:
scrolling with mouse in kdes dolphin not smooth (one scroll equals skip 3 lines more)

6.2 causes:
latest kde plasma use libinput with fewer features

6.3 solutions:
fallback to old evdev which provide more features and settings
install evdev
$ sudo pacman -S xf86-input-evdev
oen terminal and use your favorite text editor and edit xorg.conf to use evdev
$ sudo nano /etc/X11/xorg.conf.d/xorg.conf
replace any thing named libinput to evdev it should look to be like this

Section "InputClass" 
    Identifier "evdev-mouse" 
    MatchIsPointer "yes" 
    Driver "evdev" 
EndSection

save and exit, logout and login back
open kde system settings input devices -> mouse -> you will noticed that more settings are being available
navigate to advance tab and set mouse scroll lines by = 1

7 cpu is throtled up, even when idle
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7.1 problem:
computer works heavily even when idle (noticeable by fast computer fan sound, or an excessesive heat released)

7.2 causes:
1) mostly caused by a invisible high running background service that eating your resources infinitely and makes your cpu work too hard
2) you running heavy applications and your computer spec coulndt withstand it
3) your expensive nonfree dedicated graphic processor is not working properly

7.3 solutions:
1) open your system monitor eg. lxtask, ksysguard, gnome-system-monitor, etc..
locate and find out the most high cpu usage background service then try to disable them
example on kdes baloo indexer (baloo and other unstable file indexer commonly known to cause this problem especially when you had a big harddisk connected)
for kdes baloo case:
$ balooctl stop
$ balooctl disable
or using kde system settings -> search -> file search -> turn off the baloo fille indexer

2) open your system monitor check if you had an high cpu and ram usage (nearly full harddisk also can cause this)
use lightweight program alternatives if your computer spec doesnt capable of heavy liftin
example use lxde instead of gnome, use mpv instead of vlc, use midori instead of iceweasel etc..

3) dedicated graphics other than intel mainly uses an nonfree firmware thus making them less efficient on linux
you can try at least to minimized the cons by installing the apporiate free driver tolls available example:
$ sudo pacman -S laptop-mode-tools powertop tlp (etc..)(laptop components are commonly more nonfree than desktop computer)
$ sudo pacman -S bbswitch xf86-video-nouveau xf86-video-amdgpu (etc..)(find out and use the right tool for apporiate driver)

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enjoy your day, CC-BY-SA dikasp 2019

hopefully more solutions to come...
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