[LegacyTreatNonObjectAsNull]
callback EventHandlerNonNull = any (Event event);
typedef EventHandlerNonNull? EventHandler;

[LegacyTreatNonObjectAsNull]
callback OnErrorEventHandlerNonNull = any ((Event or DOMString) event, optional DOMString source, optional unsigned long lineno, optional unsigned long colno, optional any error);
typedef OnErrorEventHandlerNonNull? OnErrorEventHandler;

[LegacyTreatNonObjectAsNull]
callback OnBeforeUnloadEventHandlerNonNull = DOMString? (Event event);
typedef OnBeforeUnloadEventHandlerNonNull? OnBeforeUnloadEventHandler;

interface mixin GlobalEventHandlers {
    attribute EventHandler onabort;
    attribute EventHandler onauxclick;
    // TODO: attribute EventHandler onbeforematch;
    attribute EventHandler onblur;
    attribute EventHandler oncancel;
    attribute EventHandler oncanplay;
    attribute EventHandler oncanplaythrough;
    attribute EventHandler onchange;
    attribute EventHandler onclick;
    attribute EventHandler onclose;
    // TODO: attribute EventHandler oncontextlost;
    attribute EventHandler oncontextmenu;
    // TODO: attribute EventHandler oncontextrestored;
    attribute EventHandler oncuechange;
    attribute EventHandler ondblclick;
    attribute EventHandler ondrag;
    attribute EventHandler ondragend;
    attribute EventHandler ondragenter;
    attribute EventHandler ondragleave;
    attribute EventHandler ondragover;
    attribute EventHandler ondragstart;
    attribute EventHandler ondrop;
    attribute EventHandler ondurationchange;
    attribute EventHandler onemptied;
    attribute EventHandler onended;
    attribute OnErrorEventHandler onerror;
    attribute EventHandler onfocus;
    attribute EventHandler onformdata;
    attribute EventHandler oninput;
    attribute EventHandler oninvalid;
    attribute EventHandler onkeydown;
    attribute EventHandler onkeypress;
    attribute EventHandler onkeyup;
    attribute EventHandler onload;
    attribute EventHandler onloadeddata;
    attribute EventHandler onloadedmetadata;
    attribute EventHandler onloadstart;
    attribute EventHandler onmousedown;
    [LegacyLenientThis] attribute EventHandler onmouseenter;
    [LegacyLenientThis] attribute EventHandler onmouseleave;
    attribute EventHandler onmousemove;
    attribute EventHandler onmouseout;
    attribute EventHandler onmouseover;
    attribute EventHandler onmouseup;
    attribute EventHandler onpause;
    attribute EventHandler onplay;
    attribute EventHandler onplaying;
    attribute EventHandler onprogress;
    attribute EventHandler onratechange;
    attribute EventHandler onreset;
    attribute EventHandler onresize;
    attribute EventHandler onscroll;
    attribute EventHandler onsecuritypolicyviolation;
    attribute EventHandler onseeked;
    attribute EventHandler onseeking;
    attribute EventHandler onselect;
    attribute EventHandler onslotchange;
    attribute EventHandler onstalled;
    attribute EventHandler onsubmit;
    attribute EventHandler onsuspend;
    attribute EventHandler ontimeupdate;
    attribute EventHandler ontoggle;
    attribute EventHandler onvolumechange;
    attribute EventHandler onwaiting;
    attribute EventHandler onwebkitanimationend;
    attribute EventHandler onwebkitanimationiteration;
    attribute EventHandler onwebkitanimationstart;
    attribute EventHandler onwebkittransitionend;
    attribute EventHandler onwheel;
};

interface mixin WindowEventHandlers {
    attribute EventHandler onafterprint;
    attribute EventHandler onbeforeprint;
    attribute OnBeforeUnloadEventHandler onbeforeunload;
    attribute EventHandler onhashchange;
    attribute EventHandler onlanguagechange;
    attribute EventHandler onmessage;
    attribute EventHandler onmessageerror;
    attribute EventHandler onoffline;
    attribute EventHandler ononline;
    attribute EventHandler onpagehide;
    attribute EventHandler onpageshow;
    attribute EventHandler onpopstate;
    attribute EventHandler onrejectionhandled;
    attribute EventHandler onstorage;
    attribute EventHandler onunhandledrejection;
    attribute EventHandler onunload;
};