Add Plasma Troubleshooing Page (#440)

* Add Plasma Troubleshooing Page

Create initial page for troubleshooting Plasma
Add sections for desktop not responding, clearing Plasma cache

---------

Co-authored-by: Tracey Clark <[email protected]>
Co-authored-by: David Harder <[email protected]>
Co-authored-by: Aldair <[email protected]>

Author: 4 people

docs/user/troubleshooting/plasma.md

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+---
+title: Plasma Troubleshooting
+summary: Troubleshooting Issues With the Plasma Desktop
+---
+
+# Plasma Desktop Troubleshooting
+
+This contains fixes for various issues you might encounter with the Plasma desktop environment.
+
+## Desktop no longer responds to clicks, cursor stuck in "move" mode (cross)
+
+This is often caused by a Firefox bug. It can be triggered by various things, like moving Firefox windows.
+
+**Symptoms:**
+- Can't click on anything on the desktop.
+- Bringing up windows with keyboard shortcuts (ex: Super for the app menu, F9 for a drop down terminal) works, but they don't get focused. You can't interact with them.
+- Mouse cursor is stuck in move mode, it looks like a cross.
+
+You may not need to reboot to recover from this state. Killing all firefox processes may be all that's necessary. To do so:
+
+1. Open a virtual terminal by pressing `Ctrl+Alt+F3`.
+1. Run the following to kill all firefox windows:
+  ```bash
+  killall firefox
+  ```
+  This should close all Firefox windows.
+1. Return to the Plasma session by pressing `Ctrl+Alt+F2`.
+  You should now be able to use Plasma normally.
+
+## Application windows look corrupt / incomplete
+
+**Symptoms**
+- Application windows look corrupt. For example, NeoChat does not display room or user icons.
+- Menus in an application are blank.
+
+You may be able to fix this by clearing KDE / Plasma cache files.
+
+:::cautionImportant
+
+You should not be logged into your Plasma session while deleting the cache files, booting from a live USB is necessary.
+
+:::
+
+1. While still logged into your Plasma session, go to your home directory:
+  ```bash
+  cd
+  ```
+1. Run these commands to back up the following directories:
+  ```bash
+  cp -av ~/.kde{,.bak}
+  cp -av ~/.config{,.bak}
+  cp -av ~/.local{,.bak}
+  cp -av ~/share{,.bak}
+  ```
+  The commands create a copy of the folders. Each copy has the `.bak` extension (Example: `~/.config.bak`). These can be used to recover configuration files, if necessary.
+1. Shut down the system.
+1. Boot from a live USB, which you can create from one of the [Solus installers](https://getsol.us/download/).
+1. [Mount your hard drive's file system](./boot-rescue.md#mounting-your-system).
+1. Change to your user's directory where you mounted your file system. For example, if you used `/mount`:
+  ```bash
+  cd /mount/home/username
+  ```
+  Replace "username" with the username you use for Solus.
+  You can make sure the directory is correct by listing the files:
+  ```bash
+  ls -laH
+  ```
+  You should see the files you would usually see in your home directory when logged into Solus normally.
+1. Remove the various caches that Plasma uses.
+  Execute the following commands:
+  ```bash
+  rm -rf .kde
+  rm -rf .cache/plasmashell*
+  rm -rf .cache/org.kde.dirmodel-qml.kcache
+  rm -rf .cache/kioexec/ .cache/krunner/ .cache/ksycoca5*
+  rm -rf .cache/krunnerbookmarkrunnerfirefoxdbfile.sqlite
+
+  cd ../.local/
+  rm -rf kate/ kded5/ klipper/ knewstuff3/ kscreen/ konsole/ kwalletd/ ksysguard/ kmail2/ kcookiejar/ kactivitymanagerd/
+
+  cd ../share/
+  rm -rf dolphin kate kcookiejar kded5 keyrings klipper kmail2 knewstuff3 konsole kscreen ksysguard kwalletd kxmlgui5 plasma_engine_comic plasma plasma_notes org.kde.gwenview
+
+  cd ../.config/
+  rm -f plasma*
+  rm -rf kde* akonadi* KDE kconf_updaterc baloo* dolphinrc drkonqirc gwenviewrc kmail2rc k*rc katemetainfos
+  ```
+1. Shut down the live environment and remove the live USB drive.
+1. Reboot back into your regular Plasma session. Verify the issue is fixed.
+1. If you experience system instability, restore the previously backed up folders.
+
+  To restore an entire directory:
+  ```
+  cp -rav .kde.bak/share/config/ .kde/share/config
+  ```
+  After restoring the files or directories, restart your system.