cocoa-cb: fix double clicking the title bar

since we draw our own title bar we lose the standard functionality of
the system provided title bar. because of that we have to reimplement
the functionality of double clicking the title bar. depending on the
system preferences we want to minimize, zoom or do nothing.

Fixes #6223

video/out/cocoa-cb/window.swift

@@ -17,6 +17,31 @@
 
 import Cocoa
 
+class CustomTtitleBar: NSVisualEffectView {
+
+    // catch these events so they are not propagated to the underlying view
+    override func mouseDown(with event: NSEvent) { }
+
+    override func mouseUp(with event: NSEvent) {
+        if event.clickCount > 1 {
+            let def = UserDefaults.standard
+            var action = def.string(forKey: "AppleActionOnDoubleClick")
+
+            // macOS 10.10 and earlier
+            if action == nil {
+                action = def.bool(forKey: "AppleMiniaturizeOnDoubleClick") == true ?
+                    "Minimize" : "Maximize"
+            }
+
+            if action == "Minimize" {
+                window!.miniaturize(self)
+            } else if action == "Maximize" {
+                window!.zoom(self)
+            }
+        }
+    }
+}
+
 class Window: NSWindow, NSWindowDelegate {
 
     weak var cocoaCB: CocoaCB! = nil
@@ -113,7 +138,7 @@ class Window: NSWindow, NSWindowDelegate {
         styleMask.insert(.fullSizeContentView)
         titleBar.alphaValue = 0
         titlebarAppearsTransparent = true
-        titleBarEffect = NSVisualEffectView(frame: f)
+        titleBarEffect = CustomTtitleBar(frame: f)
         titleBarEffect!.alphaValue = 0
         titleBarEffect!.blendingMode = .withinWindow
         titleBarEffect!.autoresizingMask = [.viewWidthSizable, .viewMinYMargin]
@@ -179,6 +204,7 @@ class Window: NSWindow, NSWindowDelegate {
             titleBar.animator().alphaValue = 1
             if !isInFullscreen && !isAnimating {
                 titleBarEffect!.animator().alphaValue = 1
+                titleBarEffect!.isHidden = false
             }
         }, completionHandler: nil )
 
@@ -193,6 +219,7 @@ class Window: NSWindow, NSWindowDelegate {
         if titleBarEffect == nil { return }
         if isInFullscreen && !isAnimating {
             titleBarEffect!.alphaValue = 0
+            titleBarEffect!.isHidden = true
             return
         }
         NSAnimationContext.runAnimationGroup({ (context) -> Void in
@@ -201,6 +228,7 @@ class Window: NSWindow, NSWindowDelegate {
             titleBarEffect!.animator().alphaValue = 0
         }, completionHandler: {
             self.titleButtons.forEach { $0.isHidden = true }
+            self.titleBarEffect!.isHidden = true
         })
     }