In the system building screen, there is an option for show :

- All

- Only Improvements

- Only Ships.


Add an Option for :

- Hide


And give to the player the possibility to Hide selected improvements/ship in a system.

Example : an Improvement give industry bonus on Temperate/Teeming. But the system don't have it. So I don't want to build this improvement, and i would like to hide it in the system panel. 

So here, I never see it in the All/Only Improvements option, until I choose to unhide it.


Tough, it need an indicator number on the option, so the player can remember he is hiding elements in this system.