1 files changed, 13 insertions, 11 deletions

diff --git a/src/macos/Sources/AppDelegate.swift b/src/macos/Sources/AppDelegate.swift
index 4e91e407..cbe9cdc9 100644
--- a/src/macos/Sources/AppDelegate.swift
+++ b/src/macos/Sources/AppDelegate.swift
@@ -81,8 +81,8 @@ final class AppDelegate: NSObject, NSApplicationDelegate, PardesViewDelegate {
         // The grid and the blur are SIBLINGS in a plain container, not parent
         // and child. A transparent theme has to show something through the
         // grid, and AppKit will not blur what is behind a window unless an
-        // NSVisualEffectView asks it to — but the backdrop is hidden for every
-        // theme that brings its own background, and hiding a superview hides
+        // NSVisualEffectView asks it to. The backdrop can be hidden independently
+        // when blur is disabled or the ground is opaque; hiding a superview hides
         // its subviews with it. Nested, an opaque theme drew a blank window.
         let container = NSView(frame: NSRect(origin: .zero, size: want))
         container.autoresizesSubviews = true
@@ -460,6 +460,7 @@ final class AppDelegate: NSObject, NSApplicationDelegate, PardesViewDelegate {
     /// theme whose background happened to equal the view's starting guess
     /// would otherwise leave the window in AppKit's default clothes forever.
     private var dressed = false
+    private var appliedBlur: UInt8 = 0
 
     private func applyTheme() {
         // Both reads happen every pump, and neither may be short-circuited by
@@ -468,15 +469,17 @@ final class AppDelegate: NSObject, NSApplicationDelegate, PardesViewDelegate {
         // tick would leave one of them unworn.
         let themeChanged = view.adoptThemeBG(pardes_theme_bg())
         let opacityChanged = view.adoptWindowOpacity(pardes_window_opacity())
-        guard themeChanged || opacityChanged || !dressed else { return }
+        let blur = pardes_window_blur()
+        let blurChanged = blur != appliedBlur
+        guard themeChanged || opacityChanged || blurChanged || !dressed else { return }
+        appliedBlur = blur
+        backdrop.alphaValue = CGFloat(blur) / 100
+        backdrop.isHidden = blur == 0 || (view.themeBG != nil && view.backgroundAlpha >= 1)
         dressed = true
-        // A ground short of solid needs the same non-opaque window a
-        // background-less theme does — but not the blur behind it. The backdrop
-        // answers "this theme brings no background"; WindowOpacity says how
-        // much of the one it brings to paint, and what shows through the rest
-        // is the desktop, which is what asking for a translucent window means.
+        // Opacity paints the theme ground; blur controls the native material
+        // behind it. An opaque ground hides the backdrop without losing the
+        // requested strength, so lowering opacity restores the effect.
         if let rgb = view.themeBG {
-            backdrop.isHidden = true
             window.isOpaque = view.backgroundAlpha >= 1
             window.backgroundColor = view.backgroundAlpha < 1 ? .clear : NSColor(
                 srgbRed: CGFloat((rgb >> 16) & 0xFF) / 255,
@@ -493,10 +496,9 @@ final class AppDelegate: NSObject, NSApplicationDelegate, PardesViewDelegate {
             window.appearance = NSAppearance(named: luma > 0.5 ? .aqua : .darkAqua)
         } else {
             // Transparent: the window stops painting anything of its own and
-            // the blur takes over. isOpaque false is what lets the desktop
+            // the optional blur sits behind it. isOpaque false lets the desktop
             // reach the backdrop at all — a titled window is opaque by default
             // and would composite over it.
-            backdrop.isHidden = false
             window.isOpaque = false
             window.backgroundColor = .clear
             window.appearance = NSAppearance(named: .darkAqua)