EventButton and EventFrame widgets

[Mayron]

Hi all. I was wondering if there are any documentation or wiki articles on these newer `EventFrame` and `EventButton` widgets. Blizzard uses them a lot in their XML files. I was surprised I haven't heard much discussion online about them.

Here's an example of how to create an `EventFrame`, followed by the contents dumped to depth 2:

`/run local a = CreateFrame("EventFrame");`

["OnShow_Intrinsic"] = function: 000002106023F200, 
["HasRegistrantsForEvent"] = function: 0000021060BA9730, 
["GetCallbacksByEvent"] = function: 00000210600A3A50, 
["UnregisterEvents"] = function: 00000210600BADF0, 
["OnHide_Intrinsic"] = function: 000002106023F1C8, 
["GenerateCallbackEvents"] = function: 00000210600BB630, 
["DoesFrameHaveEvent"] = function: 00000210600A3BD8, 
["GetCallbackTable"] = function: 00000210600A3A18, 
["callbackTables"] = { 
    ["1"] = {}, 
    ["2"] = {} 
}, 
["SecureInsertEvent"] = function: 0000021060BA9780, 
["Event"] = { 
  ["OnSizeChanged"] = "OnSizeChanged", 
  ["OnShow"] = "OnShow", 
  ["OnScroll"] = "OnScroll", 
  ["OnAllowScrollChanged"] = "OnAllowScrollChanged", 
  ["OnHide"] = "OnHide" 
}, 
["RegisterCallback"] = function: 0000021060122FD0, 
["GetCallbackTables"] = function: 00000210600A39A8, 
["SetUndefinedEventsAllowed"] = function: 00000210600A39E0, 
["UnregisterCallback"] = function: 0000021060BA97D0, 
["TriggerEvent"] = function: 0000021060123050, 
["OnSizeChanged_Intrinsic"] = function: 000002106023F238, 
["RegisterCallbackWithHandle"] = function: 00000210600BB670, 
["OnLoad"] = function: 0000021060BA96E0, 
["OnLoad_Intrinsic"] = function: 000002106023F190

And here's an example of how to create an `EventButton`, followed by the contents dumped to depth 2:

`/run local a = CreateFrame("EventButton");`

["OnClick_Intrinsic"] = function: 00000184D802D790, 
["OnMouseUp_Intrinsic"] = function: 00000184D802D590, 
["HasRegistrantsForEvent"] = function: 00000185626BC670, 
["GetCallbacksByEvent"] = function: 00000184D801CB80, 
["UnregisterEvents"] = function: 00000184D8023F10, 
["OnLeave_Intrinsic"] = function: 000001854FD29568, 
["GetCallbackTables"] = function: 00000184D801CAD8, 
["SecureInsertEvent"] = function: 00000185626BC6C0, 
["GenerateCallbackEvents"] = function: 00000184D8024750, 
["TriggerEvent"] = function: 00000184D806C150, 
["OnLoad"] = function: 00000185626BC620, 
["callbackTables"] = { 
    ["1"] = {}, 
    ["2"] = {} 
}, 
["OnLoad_Intrinsic"] = function: 000001854FD294C0, 
["Event"] = { 
  ["OnSizeChanged"] = "OnSizeChanged", 
  ["OnEnter"] = "OnEnter", 
  ["OnValueChanged"] = "OnValueChanged", 
  ["OnMouseDown"] = "OnMouseDown", 
  ["OnLeave"] = "OnLeave", 
  ["OnClick"] = "OnClick", 
  ["OnMouseUp"] = "OnMouseUp" 
}, 
["RegisterCallback"] = function: 00000184D806C0D0, 
["GetCallbackTable"] = function: 00000184D801CB48, 
["SetUndefinedEventsAllowed"] = function: 00000184D801CB10, 
["UnregisterCallback"] = function: 00000185626BC710, 
["DoesFrameHaveEvent"] = function: 00000184D801CD08, 
["OnSizeChanged_Intrinsic"] = function: 000001854FD295A0, 
["RegisterCallbackWithHandle"] = function: 00000184D8024790, 
["OnEnter_Intrinsic"] = function: 000001854FD29530, 
["OnMouseDown_Intrinsic"] = function: 00000184D802D750