WowAce

            ["message"] = "Error: AddOn ag_UnitFrames attempted to call a forbidden function (FocusUnit()) from a tainted execution path.",

            ["count"] = 1,

            ["addons"] = "  Swatter, v5.5.4293 (WombatII)\n  WowheadLooter, v30201\n  NPCScan, v3.2.0.4\n  agExtras, vr708\n  agUnitFrames, vr708\n  Bartender4, v4.4.0\n  Cartographer, v2.0\n  CartographerCoordinates, v2.0\n  CartographerFoglight, v2.0\n  CartographerLookNFeel, v2.0\n  CartographerNotes, v2.0\n  CartographerWaypoints, v2.0\n  CartographerZoneInfo, v2.0\n  DBMCore, v\n  ErrorMonster, v3\n  FluidFrames, v2.3\n  FuBar, v\n  FuBarRestFu, vv1.3.2\n  MagicRunes, v1.0.63\n  MagicRunesIconDisplay, v1.0.63\n  MagicRunesRuneBars, v1.0.63\n  Mendeleev, v3.0\n  PlayerLinkMenu, v\n  Portfolio, v1.21\n  Postal, v3.2.0\n  RangeRecolor, v2.1\n  RatingBuster, v\n  RecipeBook, v\n  Recount, v\n  TipTac, v09.08.14\n  TipTacItemRef, v09.08.13\n  TipTacTalents, v09.08.13\n  (ck=2d1)\n",

            ["timestamp"] = "2009-08-17 01:33:13",

            ["context"] = "AddOn: ag_UnitFrames",

            ["stack"] = "[C]: in function `FocusUnit'\nInterface\\FrameXML\\UnitPopup.lua:1206: in function `func'\nInterface\\FrameXML\\UIDropDownMenu.lua:563: in function `UIDropDownMenuButton_OnClick'\n[string \"*:OnClick\"]:1: in function <[string \"*:OnClick\"]:1>\n",

I think this is the error when right clicking the target to set focus using menu. Here's a taint.log

10/2 23:07:22.296  Global variable UIDROPDOWNMENU_MENU_LEVEL tainted by ag_UnitFrames - Interface\FrameXML\UIDropDownMenu.lua:583 ToggleDropDownMenu()
10/2 23:07:22.296      Interface\AddOns\ag_UnitFrames\ag_UnitClass.lua:702 DropDownUnit()
10/2 23:07:22.296      Interface\AddOns\ag_UnitFrames\ag_UnitClass.lua:247 handler()
10/2 23:07:22.296      Interface\FrameXML\SecureTemplates.lua:529 SecureActionButton_OnClick()
10/2 23:07:22.296      Interface\FrameXML\SecureTemplates.lua:570
10/2 23:07:22.296  Execution tainted by ag_UnitFrames while reading UIDROPDOWNMENU_MENU_LEVEL - Interface\FrameXML\UnitPopup.lua:915 UnitPopup_OnUpdate()
10/2 23:07:22.296      UIParent:OnUpdate()
10/2 23:07:22.296  An action was blocked because of taint from ag_UnitFrames - FocusUnit()
10/2 23:07:22.296      Interface\FrameXML\UnitPopup.lua:1206 func()
10/2 23:07:22.296      Interface\FrameXML\UIDropDownMenu.lua:563 UIDropDownMenuButton_OnClick()
10/2 23:07:22.296      DropDownList1Button2:OnClick()

I updated to the newest version of AG to get rid of this error which prevents me from setting a focus target (a real problem handling defiles on LK). Unfortunately, I'm still getting it with 3.0. I don't know what else to do.