How do I restore MATE panel settings from old backup

I was playing around with the MATE Tweak tool and suddenly a stupid option removed all my panel applets and replaced with a default layout - that thing doesn't even confirm the destructive action first!

However, I do have a backup of my home folder in the old PC... What should I copy over to get my panel back? I tried looking for .mateconf, .config/mate or dconf/user to no avail - both on my new and old computers the DConf Editor didn't show anything useful under org.mate.panel, only default stuff.

If you have backup of your dconf database file, which is usually in ~/.config/dconf/user you can restore settings from that database. But some work needs to be done.

Dconf reads database values from a profile file (See wiki here). And the path of that profile file is read from the DCONF_PROFILE environment variable.

1. So, first create a file named user2 in your home directory with content like this

   user-db:user2
   

2. Put your old dconf database file in ~/.config/dconf/ directory with name user2. There should be a file with name user already.

3. Open a terminal and extract the settings from old database

   DCONF_PROFILE=~/user2 dconf dump /org/mate > ~/mate-old
   

   This will dump the values from old dconf database in key-value format in ~/mate-old file.

4. Now load the settings back into the current database

   dconf load /org/mate/ < ~/mate-old
   

This will restore most of the settings of mate.

Extra: If you want you can restore the whole database using / in place of /org/mate. But I'm not recommending this.

These preferences are stored in the dconf database, which is written to when making changes in the GUI, the gsettings CLI (where lots of panel settings can be found) or dconf CLI.

According to /usr/share/doc/dconf-gsettings-backend/README

All preferences are stored in a single large binary file.

I have determined by experiment (changing settings and observing the modification time of the file) that this single large binary file in Ubuntu MATE 16.04 is most definitely

~/.config/dconf/user

which isn't human readable, of course

$ file ~/.config/dconf/user
: GVariant Database file, version 0

If you don't have this file in your backup, then you probably can't use the backup to restore your panel settings :(