Got the same problem on 16.04. It seems the issue was caused by Unity upgrade to 7.4.5. I manually downgraded it to 7.4.0 and the issue was gone:
sudo apt-get install unity=7.4.0+16.04.20160415-0ubuntu1 libunity-core-6.0-9=7.4.0+16.04.20160415-0ubuntu1 unity-services=7.4.0+16.04.20160415-0ubuntu1 unity-schemas=7.4.0+16.04.20160415-0ubuntu1 compiz-core=1:0.9.12.2+16.04.20160415-0ubuntu1 compiz=1:0.9.12.2+16.04.20160415-0ubuntu1 compiz-plugins-default=1:0.9.12.2+16.04.20160415-0ubuntu1 compiz-gnome=1:0.9.12.2+16.04.20160415-0ubuntu1 libcompizconfig0=1:0.9.12.2+16.04.20160415-0ubuntu1 libdecoration0=1:0.9.12.2+16.04.20160415-0ubuntu1
Got the same problem on 16.04. It seems the issue was caused by Unity upgrade to 7.4.5.
I manually downgraded it to 7.4.0 and the issue was gone:
sudo apt-get install unity=7. 4.0+16. 04.20160415- 0ubuntu1 libunity- core-6. 0-9=7.4. 0+16.04. 20160415- 0ubuntu1 unity-services= 7.4.0+16. 04.20160415- 0ubuntu1 unity-schemas= 7.4.0+16. 04.20160415- 0ubuntu1 compiz- core=1: 0.9.12. 2+16.04. 20160415- 0ubuntu1 compiz= 1:0.9.12. 2+16.04. 20160415- 0ubuntu1 compiz- plugins- default= 1:0.9.12. 2+16.04. 20160415- 0ubuntu1 compiz- gnome=1: 0.9.12. 2+16.04. 20160415- 0ubuntu1 libcompizconfig 0=1:0.9. 12.2+16. 04.20160415- 0ubuntu1 libdecoration0= 1:0.9.12. 2+16.04. 20160415- 0ubuntu1