The program dev-db/dbdesigner fails to start because it needs libborqt-6.9qt2-3.so, which is found in x11-libs/kylixlibs3-borqt. so it must be added as a dependency. Moreover, the program does not recognize the new library, as it still says it's not found, even after doing env-update and source /etc/profile. I had to create a soft link to the library in /usr/lib to make the program work.
*** This bug has been marked as a duplicate of 135731 ***