V2.01:
-fixed a client/server security issue
-fixed mass center display sometimes staying behind after monitored props got deleted

V2:

-Rewrote everything from the ground up, to bring the code up to recent standards.
I have mostly focused on performance, since the previous version was quite terrible in this regard and had a lot of crap running all the time.
There should now be zero client or server operations running when the tool is not being used. Server to client data transfer is now also limited to a 100ms interval, instead of happening every frame.

-New prop selection system, that allows you to see exactly which props will be selected instead of the old and buggy system that only displayed selection area bounds.

-Added total mass display alongside the center of mass

-The local mass center of individual entities' physics object is now used as the origin point for calculations, which will improve the accuracy of the displayed center of mass. The previous version just used entities coordinate centres.

V1.21 Improved compatibility with other addons

Current version is now displayed in the Q tool menu

V1.2 Released!

-Overhauled client/server architecture:
This means the tool should now work properly in multiplayer servers.

-Fixed mass of selected props not updating:
Changing the weight of props while they are selected should now behave as expected.

-Fixed custom area radius not taking effect

-General ruggedization

Fixed an error occuring before clientside lua startup

V1.1 Added area select function

V1.0 Initial release