[geary] Don't crash when closing composer: Bug #739141

[Jim Nelson <jnelson src gnome org>]

commit 1ee017badec74fbadb6e89be18475329ec8639a3
Author: Jim Nelson <jim yorba org>
Date:   Fri Oct 31 16:59:45 2014 -0700

    Don't crash when closing composer: Bug #739141
    
    This also has the effect of avoiding excessive draft saves due to
    the multiple From: widget's changed signal firing even though the
    account didn't actually change.

 src/client/composer/composer-widget.vala |   50 ++++++++++++++++++++---------
 1 files changed, 34 insertions(+), 16 deletions(-)
---
diff --git a/src/client/composer/composer-widget.vala b/src/client/composer/composer-widget.vala
index d34b69f..e0b966f 100644
--- a/src/client/composer/composer-widget.vala
+++ b/src/client/composer/composer-widget.vala
@@ -1998,27 +1998,45 @@ public class ComposerWidget : Gtk.EventBox {
         if (compose_type != ComposeType.NEW_MESSAGE)
             return;
         
+        bool changed = false;
+        try {
+            changed = update_from_account();
+        } catch (Error err) {
+            debug("Unable to update From: Account in composer: %s", err.message);
+        }
+        
+        // if the Geary.Account didn't change and the drafts folder is open(ing), do nothing more;
+        // need to check for the drafts folder because opening it in the case of multiple From:
+        // is handled here alone, so need to open it if not already
+        if (!changed && drafts_folder != null)
+            return;
+        
+        open_drafts_folder_async.begin(cancellable_drafts);
+        reset_draft_timer();
+    }
+    
+    private bool update_from_account() throws Error {
         // Since we've set the combo box ID to the email addresses, we can
         // fetch that and use it to grab the account from the engine.
         string? id = from_multiple.get_active_id();
-        Geary.AccountInformation? new_account_info = null;
+        if (id == null)
+            return false;
         
-        if (id != null) {
-            try {
-                new_account_info = Geary.Engine.instance.get_accounts().get(id);
-                if (new_account_info != null) {
-                    account = Geary.Engine.instance.get_account_instance(new_account_info);
-                    from = new_account_info.get_from().to_rfc822_string();
-                    set_entry_completions();
-                    
-                    open_drafts_folder_async.begin(cancellable_drafts);
-                }
-            } catch (Error e) {
-                debug("Error updating account in Composer: %s", e.message);
-            }
-        }
+        // it's possible for changed signals to fire even though nothing has changed; catch that
+        // here when possible to avoid a lot of extra work
+        Geary.AccountInformation? new_account_info = Geary.Engine.instance.get_accounts().get(id);
+        if (new_account_info == null)
+            return false;
         
-        reset_draft_timer();
+        Geary.Account new_account = Geary.Engine.instance.get_account_instance(new_account_info);
+        if (new_account == account)
+            return false;
+        
+        account = new_account;
+        from = new_account_info.get_from().to_rfc822_string();
+        set_entry_completions();
+        
+        return true;
     }
     
     private void set_entry_completions() {