macosx: fixed corner case, which could lead to an empty main window in case...

macosx: fixed corner case, which could lead to an empty main window in case the video output closes prematurely
(cherry picked from commit 5c165066)

modules/gui/macosx/MainWindow.m

@@ -727,7 +727,7 @@ static VLCMainWindow *_o_sharedInstance = nil;
     if( b_nativeFullscreenMode && b_fullscreen && b_activeVideo && sender != nil )
         return;
 
-    if (b_dropzone_active && !b_activeVideo && ([[NSApp currentEvent] modifierFlags] & NSAlternateKeyMask) != 0)
+    if (b_dropzone_active && ([[NSApp currentEvent] modifierFlags] & NSAlternateKeyMask) != 0)
     {
         b_dropzone_active = NO;
         [self hideDropZone];
@@ -1148,6 +1148,7 @@ static VLCMainWindow *_o_sharedInstance = nil;
 
 - (void)hideDropZone
 {
+    b_dropzone_active = NO;
     [o_dropzone_view removeFromSuperview];
     [[o_playlist_table animator] setHidden: NO];
 }

modules/gui/macosx/intf.m

@@ -1737,7 +1737,7 @@ unsigned int CocoaKeyToVLC( unichar i_key )
     b_active_videoplayback = b_value;
     if( o_mainwindow )
     {
-        [o_mainwindow performSelectorOnMainThread:@selector(setVideoplayEnabled) withObject:nil waitUntilDone:NO];
+        [o_mainwindow performSelectorOnMainThread:@selector(setVideoplayEnabled) withObject:nil waitUntilDone:YES];
         [o_mainwindow performSelectorOnMainThread:@selector(togglePlaylist:) withObject:nil waitUntilDone:NO];
     }
 }