Here is a workaround to make DraftSight to use your desktop theme on Ubuntu 14.04 LTS 64bit.
- Create a new file named .gtkrc-2.0 inside your home folder
- Add the following line and save it.
- Edit your .profile file. It is inside your home folder and it's hidden so you have to hit Ctrl+H in order to make it visible.
- Add the following line at the end of this file and save it.
- Install gtk2-engines-murrine:i386
- Logout and then Login back in order to apply the changes