I really like the Equation Editor in the Claris Works folder. Specifically, I like the "holes" UI when writing an equation using a summation editor, for example

I really like the Equation Editor in the Claris Works folder. Specifically, I like the "holes" UI when writing an equation using a summation editor, for example. I feel like modern equation editors have lost that, but maybe I've just used the wrong ones. Does anyone have any ones they'd recommend, or pointers to more uses of 2D editors with "hole" UIs?