Added back the confirmation message in "Copy Spare / Some colors" function.

I shouldn't have removed it in r279, it happens because the spare page has 
unsaved changes and will be modified.

git-svn-id: svn://pulkomandy.tk/GrafX2/trunk@285 416bcca6-2ee7-4201-b75f-2eb2f807beb1

boutons.c

@@ -1139,7 +1139,8 @@ void Copier_certaines_couleurs(void)
 
   Menu_Tag_couleurs("Tag colors to copy",Masque_copie_couleurs,&Confirme,0, NULL);
 
-  if (Confirme)
+  if (Confirme &&
+    (!Brouillon_Image_modifiee || Demande_de_confirmation("Spare page was modified. Proceed?")))
   {
     for (Indice=0; Indice<256; Indice++)
     {