Make the back button work for the settings and subscriptions pages

(imported from commit 650c884abc9514cdfc934ae01e0a490f5f681292)

zephyr/static/js/compose.js

@@ -73,7 +73,7 @@ exports.start = function (msg_type, opts) {
         compose.message_content(opts.message);
     }
 
-    $('#sidebar a[href="#home"]').tab('show');
+    ui.change_tab_to("#home");
 
     var focus_area;
     if (opts.stream && ! opts.subject) {

zephyr/static/js/hashchange.js

@@ -6,7 +6,18 @@ var expected_hash = false;
 
 exports.changehash = function (newhash) {
     expected_hash = newhash;
+    // Some browsers reset scrollTop when changing the hash to "",
+    // so we save and restore it.
+    // http://stackoverflow.com/questions/4715073/window-location-hash-prevent-scrolling-to-the-top
+    var scrolltop;
+    if (newhash === "") {
+        scrolltop = viewport.scrollTop();
+    }
     window.location.hash = newhash;
+    util.reset_favicon();
+    if (newhash === "") {
+        viewport.scrollTop(scrolltop);
+    }
 };
 
 function hashchanged() {
@@ -19,13 +30,24 @@ function hashchanged() {
     }
 
     var hash = window.location.hash.split("/");
-    if (hash[0] === "#narrow") {
+    switch (hash[0]) {
+        case "#narrow":
+            ui.change_tab_to("#home");
             narrow.hashchanged(hash);
             ui.update_floating_recipient_bar();
-    }
+            break;
-    else if (narrow.active()) {
+        case "":
+        case "#":
+            ui.change_tab_to("#home");
             narrow.show_all_messages();
             ui.update_floating_recipient_bar();
+            break;
+        case "#subscriptions":
+            ui.change_tab_to("#subscriptions");
+            break;
+        case "#settings":
+            ui.change_tab_to("#settings");
+            break;
     }
 }
 

zephyr/static/js/ui.js

@@ -18,6 +18,10 @@ exports.home_tab_obscured = function () {
 var scroll_positions = {};
 var gravatar_stamp = 1;
 
+exports.change_tab_to = function (tabname) {
+    $('#sidebar a[href="' + tabname + '"]').tab('show');
+};
+
 exports.focus_on = function (field_id) {
     // Call after autocompleting on a field, to advance the focus to
     // the next input field.
@@ -505,9 +509,9 @@ $(function () {
         // Set the URL bar title to show the sub-page you're currently on.
         var browser_url = target_tab;
         if (browser_url === "#home") {
-            browser_url = "#";
+            browser_url = "";
         }
-        window.history.pushState("object or string", "Title", browser_url);
+        hashchange.changehash(browser_url);
     });
 
     $('#sidebar a[href="#subscriptions"]').click(subs.fetch);