You can minimize the job manager window by clicking on the minimize icon 
.
The job manager will then disappear from the screen, but the 
icon will remain in the Windows task bar:
If you click the left mouse button on this icon the job manager will be returned to the screen and set as the active application.
It can be concealed by clicking the right mouse button on it.
The various Server messages... windows that were opened can be controlled in the same way.
Warning: When a compiling job is being processed (sent to a server), the job manager icon will be animated, immediately letting you see, for instance, that a program has been sent for compiling.