To answer the FIXME, no, we shouldn't force this. The fullscreen flag implies...

To answer the FIXME, no, we shouldn't force this.  The fullscreen flag implies borderless behavior even though the flag isn't set on the window (in case fullscreen is toggled)

src/video/uikit/SDL_uikitwindow.m

@@ -69,9 +69,6 @@ static int SetupWindowData(_THIS, SDL_Window *window, UIWindow *uiwindow, SDL_bo
 
     window->driverdata = data;
 
-    // !!! FIXME: should we force this? Shouldn't specifying FULLSCREEN
-    // !!! FIXME:  imply BORDERLESS?
-    window->flags |= SDL_WINDOW_FULLSCREEN;        /* window is always fullscreen */
     window->flags |= SDL_WINDOW_SHOWN;            /* only one window on iOS, always shown */
 
     // SDL_WINDOW_BORDERLESS controls whether status bar is hidden.
@@ -84,7 +81,7 @@ static int SetupWindowData(_THIS, SDL_Window *window, UIWindow *uiwindow, SDL_bo
     } else {
         window->flags |= SDL_WINDOW_INPUT_FOCUS;  // always has input focus
 
-        if (window->flags & SDL_WINDOW_BORDERLESS) {
+        if (window->flags & (SDL_WINDOW_FULLSCREEN|SDL_WINDOW_BORDERLESS)) {
             [UIApplication sharedApplication].statusBarHidden = YES;
         } else {
             [UIApplication sharedApplication].statusBarHidden = NO;
@@ -167,7 +164,7 @@ UIKit_CreateWindow(_THIS, SDL_Window *window)
     /* ignore the size user requested, and make a fullscreen window */
     // !!! FIXME: can we have a smaller view?
     UIWindow *uiwindow = [UIWindow alloc];
-    if (window->flags & SDL_WINDOW_BORDERLESS)
+    if (window->flags & (SDL_WINDOW_FULLSCREEN|SDL_WINDOW_BORDERLESS))
         uiwindow = [uiwindow initWithFrame:[uiscreen bounds]];
     else
         uiwindow = [uiwindow initWithFrame:[uiscreen applicationFrame]];