TL;DR
Number text boxes should submit when "E" is pressed, because using letters in them is useless anyway!Why?
This is primarily in regards to the signal selection sub-menu: I've gotten used to pressing "E" all around the game to submit menus, and it would be nice to not have to press enter/use the mouse in this instance!Signal quantities, as far as I know, only accept numeric inputs and a few operator characters. So there's no design reason where pressing "E" while in the text box wouldn't submit it!