ChallengesFrame is a HIGH-strata window parented straight to UIParent and
mouse-enabled itself, not one of the three that hang off the Collections
container -- so it gets its own module and its own enable switch rather
than joining the collections group, and it deliberately skips
ApplyWindowScale and CollectionTabs: the first scales Collections, which
would resize the other three windows and not this one, and the second
skins the tab row those three share.
The panel is built as a backdrop instead of through SetTemplate. A
template's backdrop is drawn as regions of the frame and can only match
its rect, and the title sits above that rect -- the native art carries a
banner up there -- so a panel sized to the frame left the title floating
over the open world. A backdrop has points of its own, so its top edge is
pushed up over the title, measured live rather than hardcoded, with the
hit rect and the close button following it. The nine-slice is stripped
rather than run through HideArt for a related reason: the title is one of
its regions, and Hide() would take it down with the border.
The tab row is the first stock Blizzard flavour the plugin skins, so the
shared layer grows to cover it. TAB_TEXTURES picks up the Middle pieces
those name their body after, and the OnUpdate art re-check watches the
Disabled set as well -- that pair is how a stock tab draws its selected
state, so watching only the inactive half missed art returning on
whichever tab was open. Native panel tabs also interlock, each anchored
16px back into the one before it so the ornate end caps overlap, which
reads as one merged bar once the art is gone; the overlap is absorbed by
narrowing each tab rather than by spacing the row out, which would have
grown it 80px past a frame with 16px of slack. The row is pulled up flush
against the panel it belongs to, since the native tops that spanned that
gap went with the art.
Inside the Trials tab: the search box, the filter dropdown and the scroll
bar. The dropdown is the same widget as the vanity and wardrobe ones and
takes the existing handler unchanged. The search box needs its border
cleared by file, not stripped -- an EditBox draws its caret and selection
highlight as plain textures of its own, and a blind strip leaves a box
you can type in with no cursor in it.
The scroll bar needed a handler of its own. HandleScrollBar reaches for
the thumb through GetThumbTexture and then calls SetTexture on it, but
these bars are hand-built: the thumb is a Button with art of its own, and
the arrows are named off the scroll frame rather than off the bar, so it
finds neither. Both pieces are also arted lazily -- at skin time their
textures read back nil, which is why clearing them, noop'ing their
SetTexture and alpha'ing them all failed in turn -- so the art is
suppressed from OnUpdate, the same answer the tab art needed. Colours
follow ElvUI's own proportional scroll bars, and the track is left empty
rather than given a backdrop.
