Take copies of ConversationListView's selection for undo ops

Undoable operations like trashing or marking messages need to take a
copy of the conversation lists's selection so that as the selection
changes over time, the op's underlying collection doesn't also change.

src/client/application/application-client.vala

@@ -1021,13 +1021,9 @@ public class Application.Client : Gtk.Application {
         // If there was an existing active main, select the same
         // account/folder/conversation.
         MainWindow? current = this.last_active_main_window;
-        // Make a copy of the selection so the underlying collection
-        // doesn't change as the selection does.
         this.new_window.begin(
             current.selected_folder,
-            Geary.traverse(
-                current.conversation_list_view.get_selected_conversations()
-            ).to_linked_list()
+            current.conversation_list_view.copy_selected()
         );
     }
 

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

@@ -1576,7 +1576,7 @@ public class Application.MainWindow :
                 Gee.Collection<Geary.EmailIdentifier> ids =
                     new Gee.LinkedList<Geary.EmailIdentifier>();
                 foreach (Geary.App.Conversation convo in
-                         this.conversation_list_view.get_selected_conversations()) {
+                         this.conversation_list_view.get_selected()) {
                     ids.add_all(convo.get_email_ids());
                 }
                 try {
@@ -1874,13 +1874,9 @@ public class Application.MainWindow :
     private void on_conversation_activated(Geary.App.Conversation activated) {
         if (this.selected_folder != null) {
             if (this.selected_folder.special_folder_type != DRAFTS) {
-                // Make a copy of the selection so the underlying
-                // collection doesn't change as the selection does.
                 this.application.new_window.begin(
                     this.selected_folder,
-                    Geary.traverse(
-                        this.conversation_list_view.get_selected_conversations()
-                    ).to_linked_list()
+                    this.conversation_list_view.copy_selected()
                 );
             } else {
                 // TODO: Determine how to map between conversations
@@ -1974,7 +1970,7 @@ public class Application.MainWindow :
         bool starred_selected = false;
         bool unstarred_selected = false;
         foreach (Geary.App.Conversation conversation in
-                 this.conversation_list_view.get_selected_conversations()) {
+                 this.conversation_list_view.get_selected()) {
             if (conversation.is_unread())
                 unread_selected = true;
 
@@ -2031,7 +2027,7 @@ public class Application.MainWindow :
         if (location != null) {
             this.application.controller.mark_conversations.begin(
                 location,
-                this.conversation_list_view.get_selected_conversations(),
+                this.conversation_list_view.copy_selected(),
                 Geary.EmailFlags.UNREAD,
                 false,
                 (obj, res) => {
@@ -2050,7 +2046,7 @@ public class Application.MainWindow :
         if (location != null) {
             this.application.controller.mark_conversations.begin(
                 location,
-                this.conversation_list_view.get_selected_conversations(),
+                this.conversation_list_view.copy_selected(),
                 Geary.EmailFlags.UNREAD,
                 true,
                 (obj, res) => {
@@ -2069,7 +2065,7 @@ public class Application.MainWindow :
         if (location != null) {
             this.application.controller.mark_conversations.begin(
                 location,
-                this.conversation_list_view.get_selected_conversations(),
+                this.conversation_list_view.copy_selected(),
                 Geary.EmailFlags.FLAGGED,
                 true,
                 (obj, res) => {
@@ -2088,7 +2084,7 @@ public class Application.MainWindow :
         if (location != null) {
             this.application.controller.mark_conversations.begin(
                 location,
-                this.conversation_list_view.get_selected_conversations(),
+                this.conversation_list_view.copy_selected(),
                 Geary.EmailFlags.FLAGGED,
                 false,
                 (obj, res) => {
@@ -2112,7 +2108,7 @@ public class Application.MainWindow :
             this.application.controller.move_conversations_special.begin(
                 source,
                 destination,
-                this.conversation_list_view.get_selected_conversations(),
+                this.conversation_list_view.copy_selected(),
                 (obj, res) => {
                     try {
                         this.application.controller.move_conversations_special.end(res);
@@ -2131,7 +2127,7 @@ public class Application.MainWindow :
             this.application.controller.move_conversations.begin(
                 source,
                 destination,
-                this.conversation_list_view.get_selected_conversations(),
+                this.conversation_list_view.copy_selected(),
                 (obj, res) => {
                     try {
                         this.application.controller.move_conversations.end(res);
@@ -2151,7 +2147,7 @@ public class Application.MainWindow :
             this.application.controller.copy_conversations.begin(
                 source,
                 destination,
-                this.conversation_list_view.get_selected_conversations(),
+                this.conversation_list_view.copy_selected(),
                 (obj, res) => {
                     try {
                         this.application.controller.copy_conversations.end(res);
@@ -2170,7 +2166,7 @@ public class Application.MainWindow :
             this.application.controller.move_conversations_special.begin(
                 source,
                 ARCHIVE,
-                this.conversation_list_view.get_selected_conversations(),
+                this.conversation_list_view.copy_selected(),
                 (obj, res) => {
                     try {
                         this.application.controller.move_conversations_special.end(res);
@@ -2188,7 +2184,7 @@ public class Application.MainWindow :
             this.application.controller.move_conversations_special.begin(
                 source,
                 Geary.SpecialFolderType.TRASH,
-                this.conversation_list_view.get_selected_conversations(),
+                this.conversation_list_view.copy_selected(),
                 (obj, res) => {
                     try {
                         this.application.controller.move_conversations_special.end(res);
@@ -2204,7 +2200,7 @@ public class Application.MainWindow :
         Geary.FolderSupport.Remove target =
             this.selected_folder as Geary.FolderSupport.Remove;
         Gee.Collection<Geary.App.Conversation> conversations =
-            this.conversation_list_view.get_selected_conversations();
+            this.conversation_list_view.copy_selected();
         if (target != null && this.prompt_delete_conversations(conversations.size)) {
             this.application.controller.delete_conversations.begin(
                 target,

src/client/conversation-list/conversation-list-view.vala

@@ -131,11 +131,18 @@ public class ConversationListView : Gtk.TreeView, Geary.BaseInterface {
         selection.changed.connect(on_selection_changed);
     }
 
-    /** Returns a read-only collection of the current selection. */
-    public Gee.Set<Geary.App.Conversation> get_selected_conversations() {
+    /** Returns a read-only iteration of the current selection. */
+    public Gee.Set<Geary.App.Conversation> get_selected() {
         return this.selected.read_only_view;
     }
 
+    /** Returns a copy of the current selection. */
+    public Gee.Set<Geary.App.Conversation> copy_selected() {
+        var copy = new Gee.HashSet<Geary.App.Conversation>();
+        copy.add_all(this.selected);
+        return copy;
+    }
+
     public void inhibit_next_autoselect() {
         this.should_inhibit_autoselect = true;
     }
@@ -288,13 +295,11 @@ public class ConversationListView : Gtk.TreeView, Geary.BaseInterface {
             // Get the current conversation.  If it's selected, we'll apply the mark operation to
             // all selected conversations; otherwise, it just applies to this one.
             Geary.App.Conversation conversation = get_model().get_conversation_at_path(path);
-            Gee.Collection<Geary.App.Conversation> to_mark;
-            if (this.selected.contains(conversation))
-                // take a copy of currently selected for handling to
-                // the signal
-                to_mark = get_selected_conversations();
-            else
-                to_mark = Geary.Collection.single(conversation);
+            Gee.Collection<Geary.App.Conversation> to_mark = (
+                this.selected.contains(conversation)
+                ? copy_selected()
+                : Geary.Collection.single(conversation)
+            );
 
             if (read_clicked) {
                 mark_conversations(to_mark, Geary.EmailFlags.UNREAD);

src/client/conversation-viewer/conversation-viewer.vala

@@ -156,7 +156,7 @@ public class ConversationViewer : Gtk.Stack, Geary.BaseInterface {
             // XXX move the ConversationListView management code into
             // MainWindow or somewhere more appropriate
             ConversationListView conversation_list = main_window.conversation_list_view;
-            this.selection_while_composing = conversation_list.get_selected_conversations();
+            this.selection_while_composing = conversation_list.copy_selected();
             conversation_list.get_selection().unselect_all();
 
             box.vanished.connect(on_composer_closed);