fix: focusing alt-tab own windows with alt-tab had jank (closes #501)

Author: lwouis

src/logic/Window.swift

@@ -136,18 +136,22 @@ class Window {
     }
 
     func focus() {
-        // macOS bug: when switching to a System Preferences window in another space, it switches to that space,
-        // but quickly switches back to another window in that space
-        // You can reproduce this buggy behaviour by clicking on the dock icon, proving it's an OS bug
-        BackgroundWork.accessibilityCommandsQueue.asyncWithCap { [weak self] in
-            guard let self = self else { return }
-            var elementConnection = UInt32(0)
-            CGSGetWindowOwner(cgsMainConnectionId, self.cgWindowId, &elementConnection)
-            var psn = ProcessSerialNumber()
-            CGSGetConnectionPSN(elementConnection, &psn)
-            _SLPSSetFrontProcessWithOptions(&psn, self.cgWindowId, .userGenerated)
-            self.makeKeyWindow(psn)
-            self.axUiElement.focusWindow()
+        if application.runningApplication.processIdentifier == ProcessInfo.processInfo.processIdentifier {
+            App.app.showSecondaryWindow(App.app.window(withWindowNumber: Int(cgWindowId)))
+        } else {
+            // macOS bug: when switching to a System Preferences window in another space, it switches to that space,
+            // but quickly switches back to another window in that space
+            // You can reproduce this buggy behaviour by clicking on the dock icon, proving it's an OS bug
+            BackgroundWork.accessibilityCommandsQueue.asyncWithCap { [weak self] in
+                guard let self = self else { return }
+                var elementConnection = UInt32(0)
+                CGSGetWindowOwner(cgsMainConnectionId, self.cgWindowId, &elementConnection)
+                var psn = ProcessSerialNumber()
+                CGSGetConnectionPSN(elementConnection, &psn)
+                _SLPSSetFrontProcessWithOptions(&psn, self.cgWindowId, .userGenerated)
+                self.makeKeyWindow(psn)
+                self.axUiElement.focusWindow()
+            }
         }
     }
 

src/logic/events/AccessibilityEvents.swift

@@ -123,9 +123,7 @@ private func windowCreated(_ element: AXUIElement, _ pid: pid_t) throws {
 }
 
 private func focusedWindowChanged(_ element: AXUIElement, _ pid: pid_t) throws {
-    if let wid = try element.cgWindowId(),
-       pid != ProcessInfo.processInfo.processIdentifier ||
-           (App.app.preferencesWindow.isKeyWindow || App.app.feedbackWindow?.isKeyWindow ?? false) {
+    if let wid = try element.cgWindowId() {
         let axTitle = try element.title()
         let subrole = try element.subrole()
         let role = try element.role()

src/ui/App.swift

@@ -14,7 +14,7 @@ class App: AppCenterApplication, NSApplicationDelegate {
     static var app: App!
     var thumbnailsPanel: ThumbnailsPanel!
     var preferencesWindow: PreferencesWindow!
-    var feedbackWindow: FeedbackWindow?
+    var feedbackWindow: FeedbackWindow!
     var isFirstSummon = true
     var appIsBeingUsed = false
     var shortcutsShouldBeDisabled = false
@@ -51,6 +51,7 @@ class App: AppCenterApplication, NSApplicationDelegate {
             Spaces.initialDiscovery()
             Applications.initialDiscovery()
             self.preferencesWindow = PreferencesWindow()
+            self.feedbackWindow = FeedbackWindow()
             KeyboardEvents.observe()
             MouseEvents.observe()
             // TODO: undeterministic; events in the queue may still be processing; good enough for now
@@ -107,7 +108,16 @@ class App: AppCenterApplication, NSApplicationDelegate {
         appIsBeingUsed = false
         isFirstSummon = true
         MouseEvents.toggle(false)
+        hideThumbnailPanelWithoutChangingKeyWindow()
+    }
+
+    // we don't want another window to become key when the thumbnailPanel is hidden
+    func hideThumbnailPanelWithoutChangingKeyWindow() {
+        preferencesWindow.canBecomeKey_ = false
+        feedbackWindow.canBecomeKey_ = false
         thumbnailsPanel.orderOut(nil)
+        preferencesWindow.canBecomeKey_ = true
+        feedbackWindow.canBecomeKey_ = true
     }
 
     func closeSelectedWindow() {
@@ -136,19 +146,18 @@ class App: AppCenterApplication, NSApplicationDelegate {
     }
 
     @objc func showFeedbackPanel() {
-        if feedbackWindow == nil {
-            feedbackWindow = FeedbackWindow()
-        }
-        Screen.repositionPanel(feedbackWindow!, Screen.preferred(), .appleCentered)
-        App.shared.activate(ignoringOtherApps: true)
-        feedbackWindow!.makeKeyAndOrderFront(nil)
+        showSecondaryWindow(feedbackWindow)
     }
 
     @objc func showPreferencesWindow() {
-        if let preferencesWindow = preferencesWindow {
-            Screen.repositionPanel(preferencesWindow, Screen.preferred(), .appleCentered)
+        showSecondaryWindow(preferencesWindow)
+    }
+
+    func showSecondaryWindow(_ window: NSWindow?) {
+        if let window = window {
+            Screen.repositionPanel(window, Screen.preferred(), .appleCentered)
             App.shared.activate(ignoringOtherApps: true)
-            preferencesWindow.makeKeyAndOrderFront(nil)
+            window.makeKeyAndOrderFront(nil)
         }
     }
 

src/ui/FeedbackWindow.swift

@@ -6,6 +6,8 @@ class FeedbackWindow: NSWindow {
     var email: TextArea!
     var sendButton: NSButton!
     var debugProfile: NSButton!
+    var canBecomeKey_ = true
+    override var canBecomeKey: Bool { canBecomeKey_ }
 
     override init(contentRect: NSRect, styleMask style: StyleMask, backing backingStoreType: BackingStoreType, defer flag: Bool) {
         super.init(contentRect: .zero, styleMask: style, backing: backingStoreType, defer: flag)

src/ui/preferences-window/PreferencesWindow.swift

@@ -2,6 +2,8 @@ import Cocoa
 
 class PreferencesWindow: NSWindow, NSToolbarDelegate {
     var toolbarItems = [NSToolbarItem.Identifier: (Int, NSToolbarItem, NSView)]()
+    var canBecomeKey_ = true
+    override var canBecomeKey: Bool { canBecomeKey_ }
 
     override init(contentRect: NSRect, styleMask style: StyleMask, backing backingStoreType: BackingStoreType, defer flag: Bool) {
         super.init(contentRect: .zero, styleMask: style, backing: backingStoreType, defer: flag)