cocoa_common: autohide dock/menubar on fs only if on same screen

Autohide the menubar and/or dock only if they are present in the screen the
player is going to go fullscreen into. I thought the GUI would handle this for
me when I switched 0057aa476 but lack of hardware to test made me embarass
myself yet again.

I reimplemented this feature with nicer code and behaviour. The code checks
separately wether to hide menubar and dock separatly, while the old code used
a single check possibly hiding stuff without need.

Added the key checks as a some category additions to NSScreen for readability.

video/out/cocoa_common.m

@@ -74,6 +74,11 @@ static bool RightAltPressed(NSEvent *event)
 @property(nonatomic, assign, getter=hasMouseDown) BOOL mouseDown;
 @end
 
+@interface NSScreen (mpvadditions)
+- (BOOL)hasDock;
+- (BOOL)hasMenubar;
+@end
+
 struct vo_cocoa_input_queue {
     NSMutableArray *fifo;
 };
@@ -686,14 +691,19 @@ int vo_cocoa_cgl_color_size(struct vo *vo)
     struct vo_cocoa_state *s = self.videoOutput->cocoa;
 
     if (willBeFullscreen) {
+        NSApplicationPresentationOptions popts =
+            NSApplicationPresentationDefault;
+
+        if ([s->fs_screen hasMenubar])
+            popts |= NSApplicationPresentationAutoHideMenuBar;
+
+        if ([s->fs_screen hasDock])
+            popts |= NSApplicationPresentationAutoHideDock;
+
         NSDictionary *fsopts = @{
-            NSFullScreenModeWindowLevel :
-                @(NSFloatingWindowLevel),
-            NSFullScreenModeAllScreens :
-                @NO,
-            NSFullScreenModeApplicationPresentationOptions :
-                @(NSApplicationPresentationAutoHideDock |
-                  NSApplicationPresentationAutoHideMenuBar)
+            NSFullScreenModeWindowLevel : @(NSFloatingWindowLevel),
+            NSFullScreenModeAllScreens  : @NO,
+            NSFullScreenModeApplicationPresentationOptions : @(popts)
         };
 
         [s->view enterFullScreenMode:s->fs_screen withOptions:fsopts];
@@ -999,3 +1009,23 @@ int vo_cocoa_cgl_color_size(struct vo *vo)
     }
 }
 @end
+
+@implementation NSScreen (mpvadditions)
+- (BOOL)hasDock
+{
+    NSRect vF = [self visibleFrame];
+    NSRect f  = [self frame];
+    return
+        // The visible frame's width is smaller: dock is on left or right end
+        // of this method's receiver.
+        vF.size.width < f.size.width ||
+        // The visible frame's veritical origin is bigger is smaller: dock is
+        // on the bottom of this method's receiver.
+        vF.origin.y > f.origin.y;
+
+}
+- (BOOL)hasMenubar
+{
+    return [self isEqual: [NSScreen screens][0]];
+}
+@end