Refine macOS menu bar drop target icon

apps/macos-sync/Sources/CairnquireSyncApp/App.swift

@@ -81,22 +81,28 @@ class AppDelegate: NSObject, NSApplicationDelegate {
     func updateIcon(config: SyncConfig) {
         guard controller.uploadProgress == nil else { return }
         let iconName = config.iconName
-        let image = NSImage(systemSymbolName: iconName, accessibilityDescription: "Cairnquire")
-            ?? NSImage(systemSymbolName: "tray.circle.fill", accessibilityDescription: "Cairnquire")
-        dropButton.image = image
+        dropButton.image = makeMenuBarIcon(named: iconName, accessibilityDescription: "Cairnquire")
+        dropButton.setDropTargetActive(false)
     }
     
     private func updateIconForUpload(progress: Double?) {
         if progress != nil {
             // During upload: show tray.circle (outline)
-            let image = NSImage(systemSymbolName: "tray.circle", accessibilityDescription: "Uploading")
-            dropButton.image = image
+            dropButton.image = makeMenuBarIcon(named: "tray.circle", accessibilityDescription: "Uploading")
+            dropButton.setDropTargetActive(false)
         } else {
             // Upload complete: restore normal icon
             updateIcon(config: controller.config)
         }
     }
 
+    private func makeMenuBarIcon(named iconName: String, accessibilityDescription: String) -> NSImage? {
+        let image = NSImage(systemSymbolName: iconName, accessibilityDescription: accessibilityDescription)
+            ?? NSImage(systemSymbolName: "tray.circle.fill", accessibilityDescription: accessibilityDescription)
+        image?.isTemplate = true
+        return image
+    }
+    
     func bounceIcon() {
         guard let button = dropButton else { return }
         
@@ -325,19 +331,32 @@ class DropStatusButton: NSButton {
     }
     
     private func setup() {
+        isBordered = false
+        bezelStyle = .regularSquare
+        imageScaling = .scaleProportionallyDown
         registerForDraggedTypes([.fileURL])
     }
 
+    func setDropTargetActive(_ isActive: Bool) {
+        isBordered = isActive
+        contentTintColor = isActive ? .systemBlue : nil
+        needsDisplay = true
+    }
+    
     override func draggingEntered(_ sender: NSDraggingInfo) -> NSDragOperation {
-        // Tint icon slightly to indicate drop zone is active
-        if let image = self.image {
-            self.image = image.tinted(with: .systemBlue)
+        let pasteboard = sender.draggingPasteboard
+        guard pasteboard.canReadObject(forClasses: [NSURL.self], options: nil) else {
+            setDropTargetActive(false)
+            return []
         }
+
+        // Show the button frame only while the menu bar icon is a valid drop target.
+        setDropTargetActive(true)
         return .copy
     }
     
     override func draggingExited(_ sender: NSDraggingInfo?) {
-        // Restore original icon
+        setDropTargetActive(false)
         if let appDelegate = appDelegate {
             appDelegate.updateIcon(config: appDelegate.controller.config)
         }
@@ -347,9 +366,11 @@ class DropStatusButton: NSButton {
         let pasteboard = sender.draggingPasteboard
         guard let urls = pasteboard.readObjects(forClasses: [NSURL.self], options: nil) as? [URL],
               !urls.isEmpty else {
+            setDropTargetActive(false)
             return false
         }
         
+        setDropTargetActive(false)
         appDelegate?.bounceIcon()
         
         Task { @MainActor in
@@ -359,18 +380,3 @@ class DropStatusButton: NSButton {
         return true
     }
 }
-
-extension NSImage {
-    func tinted(with color: NSColor) -> NSImage {
-        let image = self.copy() as! NSImage
-        image.isTemplate = false
-        
-        let rect = NSRect(origin: .zero, size: image.size)
-        image.lockFocus()
-        color.set()
-        rect.fill(using: .sourceAtop)
-        image.unlockFocus()
-        
-        return image
-    }
-}