So let me ask.. if you use the new object capture mode in SC3 -- you can capture any one object easily -- and you would just like a faster way to capture a bunch of objects one after the other more quickly?
So in SC3, if you start an object capture, then you control+Click, you get a dialog where you can push 2 to capture another object, and so on.
So if I simply added an additional key that captured the object under the red box and immediately let you stay in the red box mode to capture more objects, that would do what you want?