fix: command+backtick not working if stage manager is on (closes #2053)

Author: lwouis

src/api-wrappers/PrivateApis.swift

@@ -203,15 +203,22 @@ func SLSRequestScreenCaptureAccess() -> UInt8
 let kAXFullscreenAttribute = "AXFullScreen"
 let kAXStatusLabelAttribute = "AXStatusLabel"
 
+enum CGSSymbolicHotKey: Int, CaseIterable {
+    case commandTab = 1
+    case commandShiftTab = 2
+    case commandKeyAboveTab = 6 // see keyAboveTabDependingOnInputSource
+}
+
 // enables/disables a symbolic hotkeys. These are system shortcuts such as command+tab or Spotlight
 // it is possible to find all the existing hotkey IDs by using CGSGetSymbolicHotKeyValue on the first few hundred numbers
 // note: the effect of enabling/disabling persists after the app is quit
 @_silgen_name("CGSSetSymbolicHotKeyEnabled") @discardableResult
-func CGSSetSymbolicHotKeyEnabled(_ hotKey: Int, _ isEnabled: Bool) -> CGError
+func CGSSetSymbolicHotKeyEnabled(_ hotKey: CGSSymbolicHotKey.RawValue, _ isEnabled: Bool) -> CGError
 
-func setNativeCommandTabEnabled(_ isEnabled: Bool) {
-    CGSSetSymbolicHotKeyEnabled(1, isEnabled) // command+tab
-    CGSSetSymbolicHotKeyEnabled(2, isEnabled) // command+shift+tab
+func setNativeCommandTabEnabled(_ isEnabled: Bool, _ hotkeys: [CGSSymbolicHotKey] = CGSSymbolicHotKey.allCases) {
+    for hotkey in hotkeys {
+        CGSSetSymbolicHotKeyEnabled(hotkey.rawValue, isEnabled)
+    }
 }
 
 // returns info about a given psn

src/logic/Preferences.swift

@@ -370,6 +370,7 @@ class Preferences {
         return "6"
     }
 
+    /// key-above-tab is ` on US keyboard, but can be different on other keyboards
     static func keyAboveTabDependingOnInputSource() -> String {
         return LiteralKeyCodeTransformer.shared.transformedValue(NSNumber(value: kVK_ANSI_Grave)) ?? "`"
     }

src/ui/preferences-window/tabs/ControlsTab.swift

@@ -136,15 +136,27 @@ class ControlsTab {
         toggleNativeCommandTabIfNeeded()
     }
 
-    private static func toggleNativeCommandTabIfNeeded() {
-        for atShortcut in shortcuts.values {
-            let shortcut = atShortcut.shortcut
-            if (shortcut.carbonModifierFlags == cmdKey || shortcut.carbonModifierFlags == (cmdKey | shiftKey)) && shortcut.carbonKeyCode == kVK_Tab {
-                setNativeCommandTabEnabled(false)
-                return
+    /// commandTab and commandKeyAboveTab are self-contained in the "nextWindowShortcut" shortcuts
+    /// but the keys of commandShiftTab can be spread between holdShortcut and a local shortcut
+    static func combinedModifiersMatch(_ modifiers1: UInt32, _ modifiers2: UInt32) -> Bool {
+        return (0..<5).contains {
+            if let holdShortcut = shortcuts[Preferences.indexToName("holdShortcut", $0)] {
+                return (holdShortcut.shortcut.carbonModifierFlags | modifiers1) == (holdShortcut.shortcut.carbonModifierFlags | modifiers2)
             }
+            return false
         }
-        setNativeCommandTabEnabled(true)
+    }
+
+    private static func toggleNativeCommandTabIfNeeded() {
+        let nativeHotkeys: [CGSSymbolicHotKey: (Shortcut) -> Bool] = [
+            .commandTab: { (shortcut) in shortcut.carbonKeyCode == kVK_Tab && shortcut.carbonModifierFlags == cmdKey },
+            .commandShiftTab: { (shortcut) in shortcut.carbonKeyCode == kVK_Tab && combinedModifiersMatch(shortcut.carbonModifierFlags, UInt32(cmdKey | shiftKey)) },
+            .commandKeyAboveTab: { (shortcut) in shortcut.carbonModifierFlags == cmdKey && shortcut.carbonKeyCode == kVK_ANSI_Grave },
+        ]
+        let overlappingHotkeys = shortcuts.values.compactMap { (atShortcut) in nativeHotkeys.first { $1(atShortcut.shortcut) }?.key }
+        let nonOverlappingHotkeys: [CGSSymbolicHotKey] = Array(Set(nativeHotkeys.keys).symmetricDifference(Set(overlappingHotkeys)))
+        setNativeCommandTabEnabled(false, overlappingHotkeys)
+        setNativeCommandTabEnabled(true, nonOverlappingHotkeys)
     }
 
     @objc static func shortcutChangedCallback(_ sender: NSControl) {