AceConfigDialog-3.0: Forward the "arg" option table member to widgets

Widgets will receive the data through the SetCustomData function, if
available, and can act on it as needed. This provides a clear lifecycle
function before layout where the data is being made available.

Author: Nevcairiel

AceConfig-3.0/AceConfigDialog-3.0/AceConfigDialog-3.0.lua

@@ -7,7 +7,7 @@ local LibStub = LibStub
 local gui = LibStub("AceGUI-3.0")
 local reg = LibStub("AceConfigRegistry-3.0")
 
-local MAJOR, MINOR = "AceConfigDialog-3.0", 91
+local MAJOR, MINOR = "AceConfigDialog-3.0", 92
 local AceConfigDialog, oldminor = LibStub:NewLibrary(MAJOR, MINOR)
 
 if not AceConfigDialog then return end
@@ -1083,6 +1083,11 @@ local function InjectInfo(control, options, option, path, rootframe, appName)
 	control:SetCallback("OnRelease", CleanUserData)
 	control:SetCallback("OnLeave", OptionOnMouseLeave)
 	control:SetCallback("OnEnter", OptionOnMouseOver)
+
+	-- forward custom arg data directly
+	if control.SetCustomData and option.arg then
+		safecall(control.SetCustomData, control, option.arg)
+	end
 end
 
 local function CreateControl(userControlType, fallbackControlType)