[Salmo]

Not a mod, is now a standard feature from ver 4.10 onwards. Hold alt-left mouse button & move mouse down & right to create a box containing the objects. Right mouse click should give you copy-paste options, also gives unselect & unselect-all options. BTW, select, copy, paste also works between missions, so you can copy from one mission & paste into another mission. It works much like most windows software.