macosx: work-around a playlist core limitation, which doesn't allow the UI to...

macosx: work-around a playlist core limitation, which doesn't allow the UI to set the currently displayed root properly, so triggering a play can lead to unwanted results (close #7484)
(cherry picked from commit 722c751deddeb6106ed18e379a1364ed85cd2f86)

Conflicts:
	modules/gui/macosx/CoreInteraction.m

modules/gui/macosx/CoreInteraction.m

@@ -79,17 +79,24 @@ static VLCCoreInteraction *_o_sharedInstance = nil;
 
 - (void)play
 {
-    playlist_t * p_playlist = pl_Get( VLCIntf );
-    bool empty;
-
-    PL_LOCK;
-    empty = playlist_IsEmpty( p_playlist );
-    PL_UNLOCK;
-
-    if( empty )
-        [[[VLCMain sharedInstance] open] openFileGeneric];
-
-    var_SetInteger( VLCIntf->p_libvlc, "key-action", ACTIONID_PLAY_PAUSE );
+    input_thread_t * p_input;
+    p_input = pl_CurrentInput(VLCIntf);
+    if (p_input) {
+        var_SetInteger(VLCIntf->p_libvlc, "key-action", ACTIONID_PLAY_PAUSE);
+        vlc_object_release(p_input);
+    } else {
+        playlist_t * p_playlist = pl_Get(VLCIntf);
+        bool empty;
+
+        PL_LOCK;
+        empty = playlist_IsEmpty(p_playlist);
+        PL_UNLOCK;
+
+        if ([[[VLCMain sharedInstance] playlist] isSelectionEmpty] && ([[[VLCMain sharedInstance] playlist] currentPlaylistRoot] == p_playlist->p_local_category || [[[VLCMain sharedInstance] playlist] currentPlaylistRoot] == p_playlist->p_ml_category))
+            [[[VLCMain sharedInstance] open] openFileGeneric];
+        else
+            [[[VLCMain sharedInstance] playlist] playItem:nil];
+    }
 }
 
 - (void)pause