macosx: only set b_nonembedded to true if they is no video inside main window

This fixes several bugs, when we start first vout in main window, but a second one
inside a extra video window.

modules/gui/macosx/MainWindow.h

@@ -86,7 +86,9 @@
 
     NSMutableArray *o_sidebaritems;
 
+    /* this is only true, when we have NO video playing inside the main window */
     BOOL              b_nonembedded;
+
     BOOL              b_podcastView_displayed;
 
     /* set to yes if we are fullscreen and all animations are over */

modules/gui/macosx/VLCVoutWindowController.m

@@ -139,7 +139,9 @@
     }
     [o_new_video_window setAlphaValue: config_GetFloat(VLCIntf, "macosx-opaqueness")];
 
+    if (!b_multiple_vout_windows)
         [[VLCMainWindow sharedInstance] setNonembedded:b_nonembedded];
+
     [o_vout_view setVoutThread:(vout_thread_t *)p_wnd->p_parent];
     [o_vout_dict setObject:[o_new_video_window autorelease] forKey:[NSValue valueWithPointer:p_wnd]];