How to change the GTK engine on Cinnamon >= 2.0

I just upgraded to Cinnamon 2.0.14 on my LMDE laptop and in this new version I am unable to change the GTK engine used. Menus and widgets in general look very ugly:

When they should look something like this:

In principle, I should be able to change this using Cinnamon's own settings app in System Settings => Themes => Other Settings => Controls:

However, while most options available in that window work (Window Borders for example), the "Controls" and "Icons" options are ignored.

Starting from version 2.0, Cinnamon has become independent of Gnome and in fact conflicts with it. I have therefore had to remove Gnome to install this version of Cinnamon which may be relevant. I do have the necessary GTK packages installed though:

$ dpkg -l | grep engines | grep gtk | awk '{printf "%s  %-26s %-22s\n",$1,$2,$3}'
ii  gtk2-engines:amd64         1:2.20.2-3            
ii  gtk2-engines-aurora        1.5.1-3               
ii  gtk2-engines-candido       0.9.1-pablo4          
ii  gtk2-engines-magicchicken  1.1.1-9               
ii  gtk2-engines-moblin        1.1.1-1.1             
ii  gtk2-engines-murrine:amd64 0.98.1.1-5            
ii  gtk2-engines-nodoka        0.7.0-1.2             
ii  gtk2-engines-oxygen:amd64  1.3.3-2               
ii  gtk2-engines-pixbuf:amd64  2.24.20-1             
ii  gtk2-engines-wonderland    1.0-8                 
ii  gtk2-engines-xfce          3.0.1-2               
ii  gtk3-engines-oxygen:amd64  1.1.4-1               
ii  gtk3-engines-unico:amd64   1.0.2-1        

So, how can I choose the GTK engine used by Cinnamon to make my new desktop pretty?