Add a Talents skin entry with an enable switch and per-window scale

The talent window, the Vanity and Wardrobe windows it switches between and
the tab row along its bottom are one feature to the player, so they get one
entry in the Skins tree and one master switch gating all three
Initialize calls together. Skinning one of them without the others reads as
a bug.

Scale is a slider per window, 0.5 to 1.5, applied as a multiplier on the
existing scale rather than an absolute -- the three don't ship at the same
size (the vanity store's frame runs about 9% larger than the others), and
that is the server's choice to keep. A setting of 1.0 leaves everything
exactly as it was.

The scale is set on Collections, not on the window itself. All three
windows and the tab row are its children, and it is the only one of them
with mouse enabled -- it is what the player drags. Scaling a window
directly left the drag target at full size, so a shrunk window had to be
grabbed by clicking outside itself, and the tab row, not being a child of
any window, kept whichever size the first-opened one gave it. Scaling the
container moves its hit area with it and the tabs follow as children.

Modules/Skinning.lua

@@ -35,6 +35,59 @@ function Skin:CloseButton(close)
 	close:Size(CLOSE_BUTTON_SIZE)
 end
 
+-- Scale is a per-frame setting rather than one shared number: the three frames
+-- don't ship at the same scale (the vanity store's is about 9% larger than the
+-- other two, measured), and that's the server's choice, so the slider is a
+-- multiplier on whatever each frame was given rather than an absolute. A
+-- setting of 1 therefore leaves every frame exactly as it came.
+--
+-- Scale is applied to Collections, the container all three windows and the tab
+-- row are children of (confirmed by probe), rather than to a window itself.
+-- Collections is also the only one of them with mouse enabled -- it's what the
+-- player drags -- so scaling a window directly shrank the art while leaving the
+-- drag target at full size, which is why a shrunk window had to be grabbed by
+-- clicking outside itself. Scaling the container moves its hit area with it,
+-- and the tabs come along as its children.
+--
+-- The setting is still per-window: only one of them is ever open, and each
+-- re-applies its own on show. The native scale is captured before anything here
+-- has written one, so re-applying can't compound.
+local CONTAINER_NAME = "Collections"
+
+local scaleKey
+
+local function GetScaleSetting(key)
+	local db = CoA.db and CoA.db.profile.skins.talentFrames
+
+	return (db and db[key]) or 1
+end
+
+function Skin:ApplyWindowScale(key)
+	local container = _G[CONTAINER_NAME]
+	if not container then return end
+
+	if not container.CoANativeScale then
+		container.CoANativeScale = container:GetScale()
+	end
+
+	-- Remembered so the slider can re-apply for whichever window is open.
+	scaleKey = key
+
+	local scale = container.CoANativeScale * GetScaleSetting(key)
+
+	if container:GetScale() ~= scale then
+		container:SetScale(scale)
+	end
+end
+
+-- Live update from the slider: a window only re-runs its own skin pass on show,
+-- and a scale change should land while one is open.
+function CoA:UpdateFrameScales()
+	if scaleKey then
+		Skin:ApplyWindowScale(scaleKey)
+	end
+end
+
 -- The talent and wardrobe frames title in Arial Narrow, the vanity store in
 -- Friz Quadrata (measured live). Arial Narrow is the one that matches the rest
 -- of the layout, so it's pinned here rather than left to the frames -- and
@@ -252,15 +305,37 @@ local function OnTabChecked(tab)
 	Skin:StripTabArt(tab)
 end
 
+-- The tab row along the bottom of the talent window is one set of buttons
+-- shared by all three windows it switches between, not one row per window,
+-- which is why it lives here rather than in any single frame's module. It
+-- doesn't need scaling of its own -- it's a child of Collections, so it follows
+-- whatever ApplyWindowScale sets.
+local COLLECTION_TAB = "CollectionsPoolFrameCollectionTabTemplate%d"
+local MAX_COLLECTION_TABS = 10
+
+function Skin:CollectionTabs(owner)
+	for i = 1, MAX_COLLECTION_TABS do
+		local tab = _G[COLLECTION_TAB:format(i)]
+		if not tab then break end
+
+		self:Tab(tab, owner)
+	end
+end
+
 -- levelParent is the frame the tab must draw above, and is only needed for tabs
 -- that aren't its children (see BumpTabLevel). Pass nil for tabs parented to
 -- the frame they belong to -- normal parent/child z-order already covers those.
 function Skin:Tab(tab, levelParent)
 	if not tab then return end
 
+	-- Set on every call rather than only the first: the collection tabs are
+	-- shared, so the frame they have to draw above is whichever window is open.
+	if levelParent then
+		tab.CoALevelParent = levelParent
+	end
+
 	if not tab.CoASkinned then
 		tab.CoASkinned = true
-		tab.CoALevelParent = levelParent
 
 		self:StripTabArt(tab)