In order to work properly, Unity Tweak Tool recommends you install the necessary packages
Just a command line way to do jackyzy823's answer:
mkdir tweak;cd tweak sudo apt-get download unity-webapps-service ar xvf * tar xvf data* sudo mv usr/share/glib-2.0/schemas/com.canonical.unity.webapps.gschema.xml /usr/share/glib-2.0/schemas/ sudo glib-compile-schemas /usr/share/glib-2.0/schemas/ cd ..; sudo rm -Rf tweak
A tricky way for this,because i do not want to download so many dependencies for
extract the file
com.canonical.unity.webapps.gschema.xml (you can see it in http://packages.ubuntu.com/trusty/amd64/unity-webapps-service/filelist) in package
unity-webapps-service,put this file to
/usr/share/glib-2.0/schemas/ and finally
sudo glib-compile-schemas /usr/share/glib-2.0/schemas/ and it works.
I had no problem installing webapps service and webapps common. My exact problem was the package
was missing. I misread the screenshot in this question, and spent more than half an hour trying to figure out why even though unity webapps service and webapps common are installed unity tweak tool is not working. Finally I found out the above package was missing instead of the one mentioned in the screenshot.
To solve this error, install the
sudo apt-get install unity-lens-files
That's it. Unity Tweak Tool is now working! (finally!)
You need is to use synaptic. Try these: