Whenever you run a program that is already running, it gives you an option to close the current or not close the current running program. Previously when you hit 'dont close', it would run the new program next to the old one. Hitting 'close' would close the old one. The current behavior is broken. When you hit 'dont close', it just keeps asking you if you want to close instead of just running the program.
There is a fix for this in the current master branch, but it is not part of 5.2.