Issue #2237 - export as, select file type (by extention) list problem

In gimp_file_proc_view_get_proc(), when there is no selected
procedure (which can happen, in particular, when searching the
list), return the "automatic" procedure and its corresponding name/
filter, if one exists, instead of bailing.

Additionally, in GimpFileDialog, use a match-all filter when
gimp_file_proc_view_get_proc() returns no filter, avoiding
CRITICALs/segfault.

(cherry picked from commit e26a220a6f)

app/widgets/gimpfiledialog.c

@@ -808,26 +808,32 @@ gimp_file_dialog_proc_changed (GimpFileProcView *view,
   GtkFileChooser *chooser = GTK_FILE_CHOOSER (dialog);
   GtkFileFilter  *filter;
   gchar          *name;
+  gchar          *label;
 
   dialog->file_proc = gimp_file_proc_view_get_proc (view, &name, &filter);
 
   if (name)
-    {
-      gchar *label = g_strdup_printf (_("Select File _Type (%s)"), name);
+    label = g_strdup_printf (_("Select File _Type (%s)"), name);
+  else
+    label = g_strdup (_("Select File _Type"));
 
   gtk_expander_set_label (GTK_EXPANDER (dialog->proc_expander), label);
 
   g_free (label);
   g_free (name);
-    }
+
   if (dialog->show_all_files)
+    g_clear_object (&filter);
+
+  if (! filter)
     {
-      g_object_unref (filter);
-      filter = gtk_file_filter_new ();
+      filter = g_object_ref_sink (gtk_file_filter_new ());
+
       gtk_file_filter_add_pattern (filter, "*");
-      g_object_ref_sink (filter);
     }
+
   gtk_file_chooser_set_filter (GTK_FILE_CHOOSER (dialog), filter);
+
   g_object_unref (filter);
 
   if (gtk_file_chooser_get_action (chooser) == GTK_FILE_CHOOSER_ACTION_SAVE)

app/widgets/gimpfileprocview.c

@@ -233,47 +233,59 @@ gimp_file_proc_view_get_proc (GimpFileProcView  *view,
 {
   GtkTreeModel        *model;
   GtkTreeSelection    *selection;
+  GimpPlugInProcedure *proc;
   GtkTreeIter          iter;
+  gboolean             has_selection;
 
   g_return_val_if_fail (GIMP_IS_FILE_PROC_VIEW (view), NULL);
 
+  if (label)  *label  = NULL;
+  if (filter) *filter = NULL;
+
   selection = gtk_tree_view_get_selection (GTK_TREE_VIEW (view));
 
-  if (gtk_tree_selection_get_selected (selection, &model, &iter))
-    {
-      GimpPlugInProcedure *proc;
+  has_selection = gtk_tree_selection_get_selected (selection, &model, &iter);
+
+  /* if there's no selected item, we return the "automatic" procedure, which,
+   * if exists, is the first item.
+   */
+  if (! has_selection)
+    {
+      model = gtk_tree_view_get_model (GTK_TREE_VIEW (view));
+
+      if (! gtk_tree_model_get_iter_first (model, &iter))
+        return NULL;
+    }
 
-      if (label && filter)
-        gtk_tree_model_get (model, &iter,
-                            COLUMN_PROC,   &proc,
-                            COLUMN_LABEL,  label,
-                            COLUMN_FILTER, filter,
-                            -1);
-      else if (label)
-        gtk_tree_model_get (model, &iter,
-                            COLUMN_PROC,   &proc,
-                            COLUMN_LABEL,  label,
-                            -1);
-      else if (filter)
-        gtk_tree_model_get (model, &iter,
-                            COLUMN_PROC,   &proc,
-                            COLUMN_FILTER, filter,
-                            -1);
-      else
   gtk_tree_model_get (model, &iter,
                       COLUMN_PROC, &proc,
                       -1);
 
   if (proc)
+    {
       g_object_unref (proc);
 
-      return proc;
+      /* there's no selected item, and no "automatic" procedure.  return NULL.
+       */
+      if (! has_selection)
+        return NULL;
     }
 
   if (label)
-    *label = NULL;
+    {
+      gtk_tree_model_get (model, &iter,
+                          COLUMN_LABEL, label,
+                          -1);
+    }
 
-  return NULL;
+  if (filter)
+    {
+      gtk_tree_model_get (model, &iter,
+                          COLUMN_FILTER, filter,
+                          -1);
+    }
+
+  return proc;
 }
 
 gboolean