Make "d" and "u" scroll up and down a page instead of closing and restoring tabs. This implements #274.

The motivation behind this change is that scrolling a page is far more common than
closing a tab, and so those actions should be on a hotkey which doesn't require a modifier.
Once you get used to scrolling without hitting ctrl, you won't be able to go back.

For existing users, this change also adds a custom mapping for them in their preferences to preserve
the old behavior as they upgrade from 1.21 to 1.22.

3 files changed, 24 insertions, 3 deletions

diff --git a/background_page.html b/background_page.html
index 87b3c9ad..d98967b4 100644
--- a/background_page.html
+++ b/background_page.html
@@ -686,6 +686,21 @@
     if (localStorage["keyMappings"])
       parseCustomKeyMappings(localStorage["keyMappings"]);
 
+    // In version 1.22, we changed the mapping for "d" and "u" to be scroll page down/up instead of close
+    // and restore tab. For existing users, we want to preserve existing behavior for them by adding some
+    // custom key mappings on their behalf.
+    if (localStorage.previousVersion == "1.21") {
+      var customKeyMappings = localStorage["keyMappings"] || "";
+      if ((keyToCommandRegistry["d"] || {}).command == "scrollPageDown")
+        customKeyMappings += "\nmap d removeTab";
+      if ((keyToCommandRegistry["u"] || {}).command == "scrollPageUp")
+        customKeyMappings += "\nmap u restoreTab";
+      if (customKeyMappings != "") {
+        localStorage["keyMappings"] = customKeyMappings;
+        parseCustomKeyMappings(customKeyMappings);
+      }
+    }
+
     populateValidFirstKeys();
     populateSingleKeyCommands();
     if (shouldShowUpgradeMessage())
diff --git a/commands.js b/commands.js
index f2b19467..de70a0a9 100644
--- a/commands.js
+++ b/commands.js
@@ -99,6 +99,12 @@ function clearKeyMappingsAndSetDefaults() {
     "zL": "scrollToRight",
     "<c-e>": "scrollDown",
     "<c-y>": "scrollUp",
+
+    // scrollPageDown and scrollPageUp are mapped to two keys because they are very common actions so we
+    // want them to be mapped without a modifier key, but we also want to be faithful to Vim convention which
+    // has them on ctrl+D and ctrl+U.
+    "d": "scrollPageDown",
+    "u": "scrollPageUp",
     "<c-d>": "scrollPageDown",
     "<c-u>": "scrollPageUp",
     "<c-f>": "scrollFullPageDown",
@@ -137,8 +143,8 @@ function clearKeyMappingsAndSetDefaults() {
     "gT": "previousTab",
 
     "t": "createTab",
-    "d": "removeTab",
-    "u": "restoreTab",
+    "x": "removeTab",
+    "X": "restoreTab",
 
     "gf": "nextFrame"
   };
diff --git a/options.html b/options.html
index 344fc01d..bfa01450 100644
--- a/options.html
+++ b/options.html
@@ -83,7 +83,7 @@
     "userDefinedLinkHintCss", "keyMappings"];
 
   var postSaveHooks = {
-    "keyMappings": function (value) {
+    keyMappings: function (value) {
       backgroundPage = chrome.extension.getBackgroundPage();
       backgroundPage.clearKeyMappingsAndSetDefaults();
       backgroundPage.parseCustomKeyMappings(value);