Plugins: Actually implement info bar plugin priority

Now that InfoBarStack supports a priority queue, use that for folder
and email stacks, and set the required priority property when
constructing info bars for plugins, so that the highest priority
info bar is always shown.

src/client/application/application-email-plugin-context.vala

@@ -42,7 +42,7 @@ internal class Application.EmailPluginContext :
                     main.conversation_viewer.current_list.add_email_info_bar(
                         id,
                         new Components.InfoBar.for_plugin(
-                            info_bar, this.action_group_name
+                            info_bar, this.action_group_name, (int) priority
                         )
                     );
                 }

src/client/application/application-folder-plugin-context.vala

@@ -41,7 +41,7 @@ internal class Application.FolderPluginContext :
                 if (main.selected_folder == folder) {
                     main.conversation_list_info_bars.add(
                         new Components.InfoBar.for_plugin(
-                            info_bar, this.action_group_name
+                            info_bar, this.action_group_name, (int) priority
                         )
                     );
                 }

src/client/application/application-main-window.vala

@@ -283,7 +283,7 @@ public class Application.MainWindow :
     public ConversationViewer conversation_viewer { get; private set; }
 
     public Components.InfoBarStack conversation_list_info_bars {
-        get; private set; default = new Components.InfoBarStack(SINGLE);
+        get; private set; default = new Components.InfoBarStack(PRIORITY_QUEUE);
     }
 
     public StatusBar status_bar { get; private set; default = new StatusBar(); }

src/client/components/components-info-bar.vala

@@ -73,7 +73,8 @@ public class Components.InfoBar : Gtk.InfoBar {
     }
 
     public InfoBar.for_plugin(Plugin.InfoBar plugin,
-                              string action_group_name) {
+                              string action_group_name,
+                              int priority) {
         this(plugin.status, plugin.description);
         this.show_close_button = plugin.show_close_button;
 
@@ -87,6 +88,8 @@ public class Components.InfoBar : Gtk.InfoBar {
             add_plugin_button(plugin.primary_button, action_group_name);
         }
 
+        set_data<int>(InfoBarStack.PRIORITY_QUEUE_KEY, priority);
+
         show_all();
     }
 

ui/conversation-message.ui

@@ -482,6 +482,7 @@
                 <property name="visible">False</property>
                 <property name="can_focus">False</property>
                 <property name="shadow_type">none</property>
+                <property name="algorithm">priority-queue</property>
               </object>
               <packing>
                 <property name="left_attach">0</property>