fix: more robust screen-recording permission check

alt-tab-macos/api-wrappers/PrivateApis.swift

@@ -128,6 +128,12 @@ func CGSCopySpacesForWindows(_ cid: CGSConnectionID, _ mask: CGSSpaceMask.RawVal
 @_silgen_name("CGSGetWindowLevel") @discardableResult
 func CGSGetWindowLevel(_ cid: CGSConnectionID, _ wid: CGWindowID, _ level: inout CGWindowLevel) -> CGError
 
+// returns status of the checkbox in System Preferences > Security & Privacy > Privacy > Screen Recording
+// returns 1 if checked or 0 if unchecked; also prompts the user the first time if unchecked
+@_silgen_name("SLSRequestScreenCaptureAccess") @discardableResult
+func SLSRequestScreenCaptureAccess() -> UInt8
+
+
 
 
 // ------------------------------------------------------------

alt-tab-macos/logic/SystemPermissions.swift

@@ -16,9 +16,7 @@ class SystemPermissions {
 
     static func ensureScreenRecordingCheckboxIsChecked() {
         guard #available(OSX 10.15, *) else { return }
-        // there is no API to check this permission; we try to get a screenshot to check indirectly
-        let firstWindow = CGWindow.windows(.optionOnScreenOnly)[0]
-        if let cgId = firstWindow.id(), cgId.screenshot() == nil {
+        if SLSRequestScreenCaptureAccess() != 1 {
             debugPrint("Before using this app, you need to give permission in System Preferences > Security & Privacy > Privacy > Screen Recording.",
                     "Please authorize and re-launch.",
                     "See https://dropshare.zendesk.com/hc/en-us/articles/360033453434-Enabling-Screen-Recording-Permission-on-macOS-Catalina-10-15-",

alt-tab-macos/ui/App.swift

@@ -22,8 +22,8 @@ class App: NSApplication, NSApplicationDelegate, NSWindowDelegate {
     }
 
     func applicationDidFinishLaunching(_ aNotification: Notification) {
-        SystemPermissions.ensureScreenRecordingCheckboxIsChecked()
         SystemPermissions.ensureAccessibilityCheckboxIsChecked()
+        SystemPermissions.ensureScreenRecordingCheckboxIsChecked()
         Preferences.loadFromDiskAndUpdateValues()
         statusItem = StatusItem.make(self)
         initPreferencesDependentComponents()