The Case of The Missing Dropshadow on Cinnamon

I've noticed, right after installing Linux Mint Cinnamon (32 bits of course) on the T60 that there was a missing drip shadow effect on the topside of the windows.
This happened after installing, during the USB booted session all the drop shadows were there (see the screen shot on the link above), and the compare that with the screen shot on the right.
After making the update to Linux Mint 17.3 all the shadows are back and in place, see the screen shot on the left.