things i tried (rebooting after each of them):

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dconf reset -f /org/compiz/
setsid unity

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sudo service lightdm stop
rm ~/.config/dconf/user
sudo service lightdm start

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sudo apt-get install compizconfig-settings-manager
ccsm
-> then select unity plugin and enable it

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sudo apt-get install --reinstall ubuntu-desktop

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cd ~
mv .config .config.old
-> then logout+login