feat: show alttab on display with active menubar when needed (#2107)

closes #2107

src/api-wrappers/PrivateApis.swift

@@ -138,7 +138,7 @@ func CGSCopyWindowsWithOptionsAndTags(_ cid: CGSConnectionID, _ owner: Int, _ sp
 // returns the current space ID on the provided display UUID
 // * macOS 10.10+
 @_silgen_name("CGSManagedDisplayGetCurrentSpace")
-func CGSManagedDisplayGetCurrentSpace(_ cid: CGSConnectionID, _ displayUuid: CFString) -> CGSSpaceID
+func CGSManagedDisplayGetCurrentSpace(_ cid: CGSConnectionID, _ displayUuid: ScreenUuid) -> CGSSpaceID
 
 // adds the provided windows to the provided spaces
 // * macOS 10.10-12.2
@@ -251,6 +251,11 @@ func CGSSpaceGetType(_ cid: CGSConnectionID, _ sid: CGSSpaceID) -> CGSSpaceType
 @_silgen_name("CGSSpaceAddWindowsAndRemoveFromSpaces")
 func CGSSpaceAddWindowsAndRemoveFromSpaces(_ cid: CGSConnectionID, _ sid: CGSSpaceID, _ wid: NSArray, _ notSure: Int) -> Void
 
+// get the display UUID with the active menubar (other menubar are dimmed)
+@_silgen_name("CGSCopyActiveMenuBarDisplayIdentifier")
+func CGSCopyActiveMenuBarDisplayIdentifier(_ cid: CGSConnectionID) -> ScreenUuid
+
+
 // ------------------------------------------------------------
 // below are some notes on some private APIs I experimented with
 // ------------------------------------------------------------
@@ -263,7 +268,7 @@ func CGSSpaceAddWindowsAndRemoveFromSpaces(_ cid: CGSConnectionID, _ sid: CGSSpa
 //// returns true if the current screen is animating
 //// useful to detect Spaces transitions, windows going fullscreen, etc
 //@_silgen_name("SLSManagedDisplayIsAnimating")
-//func SLSManagedDisplayIsAnimating(_ cid: CGSConnectionID, _ displayUuid: CFString) -> Bool
+//func SLSManagedDisplayIsAnimating(_ cid: CGSConnectionID, _ displayUuid: ScreenUuid) -> Bool
 
 //@_silgen_name("CGSGetSymbolicHotKeyValue")
 //func CGSGetSymbolicHotKeyValue(_ hotKey: Int, _ options: inout UInt32, _ keyCode: inout UInt32, _ modifiers: inout UInt32) -> CGError

src/logic/NSScreen.swift

@@ -26,19 +26,27 @@ extension NSScreen {
     }
 
     // NSScreen.main docs are incorrect. It stopped returning the screen with the key window in macOS 10.9
+
     // see https://stackoverflow.com/a/56268826/2249756
     // There are a few cases where .main doesn't return the screen with the key window:
     //   * if the active screen shows a fullscreen app, it always returns screens[0]
     //   * if NSScreen.screensHaveSeparateSpaces == false, and key window is on another screen than screens[0], it still returns screens[0]
     // we find the screen with the key window ourselves manually
     static func active() -> NSScreen? {
-        if let app = Applications.find(NSWorkspace.shared.frontmostApplication?.processIdentifier),
-           let focusedWindow = app.focusedWindow {
-            return NSScreen.screens.first { focusedWindow.isOnScreen($0) }
+        if let app = Applications.find(NSWorkspace.shared.frontmostApplication?.processIdentifier) {
+            if let focusedWindow = app.focusedWindow {
+                return NSScreen.screens.first { focusedWindow.isOnScreen($0) }
+            }
+            return NSScreen.withActiveMenubar()
         }
         return nil
     }
 
+    // there is only 1 active menubar. Other screens will show their menubar dimmed
+    static func withActiveMenubar() -> NSScreen? {
+        return NSScreen.screens.first { CGSCopyActiveMenuBarDisplayIdentifier(cgsMainConnectionId) == $0.uuid() }
+    }
+
     static func withMouse() -> NSScreen? {
         return NSScreen.screens.first { NSMouseInRect(NSEvent.mouseLocation, $0.frame, false) }
     }