The C version of looping over buttons and other items was weakly typed, causing runtime errors, and also C doesn't know how to iterate in abstract, so it was full of callbacks with user-defined data. Moving this to Rust, iteration is made of simple loops, and compile-time type-checked, at the cost of some more verbose code.
Each Button has a KeyState, which may be shared with other buttons. The list of pressed and locked buttons is used as a list of keys, causing a search for the button in the current view.
