[8] イベントオブジェクトは、関連対象を持ちます。
既定値は null です。 >>7
[9] 関連対象は、イベント経路の各要素の構成要素でもあります。 dispatch でイベントオブジェクトの関連対象の設定に使われます。
[1] Web Applications 1.0 r7791 Add a .relatedTarget attribute on 'show' events for <menu> elements. ( ( 版)) <http://html5.org/tools/web-apps-tracker?from=7790&to=7791>
[2] Web Applications 1.0 r7792 Set the .relatedTarget attribute on 'click' events for <menuitem> elements (and their master commands) properly. ( ( 版)) <http://html5.org/tools/web-apps-tracker?from=7791&to=7792>
[3] Web Applications 1.0 r8396 Make some dragleave and dragenter events have a relatedTarget. ( ( 版)) <http://html5.org/tools/web-apps-tracker?from=8395&to=8396>
[4] IRC logs: freenode / #whatwg / 20140508 ( ( 版)) <http://krijnhoetmer.nl/irc-logs/whatwg/20140508>
[5] Fix #486: Fix 'get the parent' for relatedTarget ( (hayatoito著, )) <https://github.com/w3c/webcomponents/commit/b1433e5f3a013ca825f02fb8f7b0e9d6217c0125>
[6] Shadow: define event's relatedTarget handling (hayatoito著, ) <https://github.com/whatwg/dom/commit/ef69a247681532e6102ced9a78aabf7f7a536108>
[10] Clarify the relatedTarget definition for pointerevents (#190) (NavidZ著, ) <https://github.com/w3c/pointerevents/commit/beb2b009087f547393267355648506af12f5aa1c>
[11] Clear event's target and relatedTarget when dispatch ends at a shadow… (TakayoshiKochi著, ) <https://github.com/whatwg/dom/commit/9ada239e14fe7964577276ef9d8972069e665247>
[12] Event.target should return null after dispatch is complete, when stopped at ShadowRoot · Issue #511 · whatwg/dom () <https://github.com/whatwg/dom/issues/511>
[13] Set event.target to null when dispatching finishes at ShadowRoot by TakayoshiKochi · Pull Request #513 · whatwg/dom () <https://github.com/whatwg/dom/pull/513>
[14] "create an event" doesn't work for certain UI events · Issue #414 · whatwg/dom () <https://github.com/whatwg/dom/issues/414>