[gimp] Fix plugin focus issues on osx

[Michael Natterer <mitch src gnome org>]

commit ac26671eb60877995d27acd547f45d06b0480e5f
Author: Oleksii Samorukov <samm os2 kiev ua>
Date:   Thu Oct 18 09:26:05 2018 +0200

    Fix plugin focus issues on osx
    
    GTK/OSX does not automatically assign focus to the new windows (upstream
    issue), so activateIgnoringOtherApps is called. However, if it is called
    before gtk initialized it may cause number of focus issues.
    
    (cherry picked from commit 3adf4a4861ba0641e64caaf6fd80a794da7687a9)

 libgimp/gimpui.c | 14 +++++++++++++-
 1 file changed, 13 insertions(+), 1 deletion(-)
---
diff --git a/libgimp/gimpui.c b/libgimp/gimpui.c
index 1cea20246b..938925d5c1 100644
--- a/libgimp/gimpui.c
+++ b/libgimp/gimpui.c
@@ -63,6 +63,10 @@ static void      gimp_window_transient_realized (GtkWidget     *window,
 static gboolean  gimp_window_set_transient_for  (GtkWindow     *window,
                                                  GdkWindow     *parent);
 
+#ifdef GDK_WINDOWING_QUARTZ
+static void      gimp_osx_focus_window          (void);
+#endif
+
 
 static gboolean gimp_ui_initialized = FALSE;
 
@@ -177,7 +181,7 @@ gimp_ui_init (const gchar *prog_name,
   gimp_dialogs_show_help_button (gimp_show_help_button ());
 
 #ifdef GDK_WINDOWING_QUARTZ
-  [NSApp activateIgnoringOtherApps:YES];
+  g_idle_add ((GSourceFunc) gimp_osx_focus_window, NULL);
 #endif
 
   gimp_ui_initialized = TRUE;
@@ -405,3 +409,11 @@ gimp_window_set_transient_for (GtkWindow *window,
 
   return FALSE;
 }
+
+#ifdef GDK_WINDOWING_QUARTZ
+static void
+gimp_osx_focus_window (void)
+{
+  [NSApp activateIgnoringOtherApps:YES];
+}
+#endif