Missing hooks

[tassoevan]

• a hook to say if the page is visible or not;
• a hook to attach hotkeys;
• hooks for element states (e.g. useHover());
• a useDrop() hook for drag'n'drop;
• a useControlledState() hook to handle defaultValue/value/onChange props (for controlled/uncontrolled input state);
• hooks for focus trapping;
• hooks to handle scrolling (i.e. detect if scrolled to bottom, use auto scroll etc.).

[tassoevan]

Also, a hook to get/set CSS custom properties.