Unless you're on a call, all windows respect the orientation mask of the

primary app visible VC.

Fixes:
- Avoid flicker when forgrounding onboarding while in landscape
- Fix status bar in landscape while fingerprint is portrait, same with device linker

Signal/src/AppDelegate.m

@@ -967,13 +967,22 @@ static NSTimeInterval launchStartedAt;
 - (UIInterfaceOrientationMask)application:(UIApplication *)application
     supportedInterfaceOrientationsForWindow:(nullable UIWindow *)window
 {
-    if (self.windowManager.hasCall) {
+    if (self.hasCall) {
         OWSLogInfo(@"has call");
         // The call-banner window is only suitable for portrait display
         return UIInterfaceOrientationMaskPortrait;
     }
 
-    return UIInterfaceOrientationMaskAllButUpsideDown;
+    UIViewController *_Nullable rootViewController = self.window.rootViewController;
+    if (!rootViewController) {
+        return UIInterfaceOrientationMaskAllButUpsideDown;
+    }
+    return rootViewController.supportedInterfaceOrientations;
+}
+
+- (BOOL)hasCall
+{
+    return self.windowManager.hasCall;
 }
 
 #pragma mark Push Notifications Delegate Methods

SignalMessaging/ViewControllers/OWSNavigationController.m

@@ -199,8 +199,8 @@ NS_ASSUME_NONNULL_BEGIN
 
 - (UIInterfaceOrientationMask)supportedInterfaceOrientations
 {
-    if (self.topViewController) {
-        return self.topViewController.supportedInterfaceOrientations;
+    if (self.visibleViewController) {
+        return self.visibleViewController.supportedInterfaceOrientations;
     } else {
         return UIInterfaceOrientationMaskAllButUpsideDown;
     }