W-990: render the picker glass with public API only

Sources/Mojito/Util/PopoverGlass.swift

@@ -1,20 +1,18 @@
 import AppKit
 import SwiftUI
 
-/// The system emoji picker's Liquid Glass, for our borderless panels. A bare
-/// `NSGlassEffectView` renders the clearer regular glass, which reads as a
-/// flat grey slab over light content. NSPopover hosts the same view with the
-/// private `_variant` 20, which is frostier.
+/// The system emoji picker's Liquid Glass, for our borderless panels, from
+/// public API only. NSPopover gets its look from a private glass variant,
+/// but those are numbered, and macOS 27.2 renumbered them: the number we
+/// once borrowed now renders a clear lens that hides the panel's edges.
 ///
-/// Even variant 20 sits darker than the system picker, which reads ~239
-/// over light content and ~115 over black, where bare glass gives ~232 and
-/// 71. A 0.25 white veil lands on both; a heavier one turns the panel into
-/// a light slab over dark backdrops and hides what's behind it.
+/// Light mode is clear glass under a 0.25 white veil, which reads like the
+/// system picker (~247 over white, ~117 over black). Regular glass reads
+/// greyer over white and lifts dark backdrops into a light slab.
 ///
 /// Dark mode keeps the regular glass, unveiled. Over a bright backdrop
-/// variant 20 turns light grey while the content stays dark-scheme, leaving
-/// white text on light grey (NSPopover has the same problem; our rows are
-/// text, so it matters more here).
+/// clear glass turns light grey while the content stays dark-scheme,
+/// leaving white text on light grey.
 @available(macOS 26.0, *)
 enum PopoverGlass {
     private static let lightVeil = NSColor.white.withAlphaComponent(0.25).cgColor
@@ -41,15 +39,9 @@ enum PopoverGlass {
 
     /// Call whenever the panel's appearance is (re)set.
     static func match(_ glass: NSGlassEffectView, to appearance: NSAppearance) {
-        // Assigning `style` rewrites the private variant, even when the
-        // style is unchanged — that's what undoes a previous light-mode pass.
-        glass.style = .regular
         let isDark = appearance.bestMatch(from: [.aqua, .darkAqua]) == .darkAqua
+        glass.style = isDark ? .regular : .clear
         glass.contentView?.layer?.backgroundColor = isDark ? nil : lightVeil
-        // KVC on a missing key raises, so if a future macOS drops the key
-        // this degrades to the regular glass.
-        guard !isDark, glass.responds(to: NSSelectorFromString("set_variant:")) else { return }
-        glass.setValue(20, forKey: "_variant")
     }
 }