diff --git a/common/content/commands.js b/common/content/commands.js
index 727b234b..16b14bc1 100644
--- a/common/content/commands.js
+++ b/common/content/commands.js
@@ -170,14 +170,9 @@ const Command = Class("Command", {
      * @see Commands#parseArgs
      */
     parseArgs: function (args, complete, extra) commands.parseArgs(args, {
-        allowUnknownOptions: !!this.allowUnknownOptions,
-        argCount: this.argCount,
+        __proto__: this,
         complete: complete,
-        extra: extra,
-        hereDoc: this.hereDoc,
-        keepQuotes: !!this.keepQuotes,
-        literal: this.literal,
-        options: this.options
+        extra: extra
     }),
 
     /**
diff --git a/common/content/options.js b/common/content/options.js
index e10739e0..c462e26c 100644
--- a/common/content/options.js
+++ b/common/content/options.js
@@ -453,12 +453,14 @@ const Option = Class("Option", {
         let res = [];
         Option._splitAt = 0;
         do {
+            if (count !== undefined)
+                value = value.slice(1);
             var [count, arg, quote] = Commands.parseArg(value, /,/, keepQuotes);
             Option._quote = quote; // FIXME
             res.push(arg);
             if (value.length > count)
                 Option._splitAt += count + 1;
-            value = value.slice(count + 1);
+            value = value.slice(count);
         } while (value.length);
         return res;
     },
@@ -494,22 +496,26 @@ const Option = Class("Option", {
         },
 
         stringmap: function (operator, values, scope, invert) {
-            values = Array.concat(values);
-            orig = [k + ":" + v for ([k, v] in Iterator(this.values))];
+            let res = update({}, this.values);
 
             switch (operator) {
+            // The result is the same.
             case "+":
-                return array.uniq(Array.concat(orig, values), true);
             case "^":
-                // NOTE: Vim doesn't prepend if there's a match in the current value
-                return array.uniq(Array.concat(values, orig), true);
+                return update(res, values);
             case "-":
-                return orig.filter(function (item) values.indexOf(item) == -1);
+                for (let [k, v] in Iterator(values))
+                    if (v === res[k])
+                        delete res[k];
+                return res;
             case "=":
                 if (invert) {
-                    let keepValues = orig.filter(function (item) values.indexOf(item) == -1);
-                    let addValues  = values.filter(function (item) self.values.indexOf(item) == -1);
-                    return addValues.concat(keepValues);
+                    for (let [k, v] in Iterator(values))
+                        if (v === res[k])
+                            delete res[k];
+                        else
+                            res[k] = v;
+                    return res;
                 }
                 return values;
             }
@@ -1412,6 +1418,7 @@ const Options = Module("options", {
                 return;
             }
 
+            let extra = {};
             switch (opt.type) {
             case "boolean":
                 if (!completer)
@@ -1425,8 +1432,13 @@ const Options = Module("options", {
             case "stringmap":
             case "regexmap":
                 let vals = Option.splitList(context.filter);
-                target = vals.pop() || "";
-                Option._splitAt += target.indexOf(":") ? target.indexOf(":") + 1 : 0;
+                let target = vals.pop() || "";
+                let [count, key, quote] = Commands.parseArg(target, /:/, true);
+                let split = Option._splitAt;
+                extra.key = Option.dequote(key);
+                extra.value = count < target.length ? Option.dequote(target.substr(count + 1)) : null;
+                extra.values = opt.parseValues(vals.join(","));
+                Option._splitAt = split + (extra.value == null ? 0 : count + 1);
                 break;
             }
             // TODO: Highlight when invalid
@@ -1445,7 +1457,7 @@ const Options = Module("options", {
                     context.filters.push(function (i) curValues.indexOf(i.text) > -1);
             }
 
-            let res = completer.call(opt, context);
+            let res = completer.call(opt, context, extra);
             if (res)
                 context.completions = res;
         };
diff --git a/common/locale/en-US/options.xml b/common/locale/en-US/options.xml
index 6491919c..5f433c82 100644
--- a/common/locale/en-US/options.xml
+++ b/common/locale/en-US/options.xml
@@ -51,7 +51,7 @@
     <dd>
         A comma-separated list of regular expressions. Expressions may be
         prefixed with a <em>!</em>, in which case the match will be negated. A
-        literal <em>!</em> at the begining of the expression may be matched
+        literal <em>!</em> at the beginning of the expression may be matched
         with <em>[!]</em> or by placing the regular expression in quotes.
         Generally, the first matching regular expression is used. Any comma
         appearing within single or double quotes, or prefixed with a
@@ -376,7 +376,7 @@
         </p>
 
         <example>
-            To enable autocompletion for everything but <ex>:history</ex> or
+            To enable auto-completion for everything but <ex>:history</ex> or
             <ex>:bmarks</ex>, you would choose a value such as
             <str delim="'">!/ex/bmarks,.?</str>
         </example>
@@ -401,7 +401,7 @@
     <default>on</default>
     <description>
         <p>
-            Replace occurences of ! with the previous command when
+            Replace occurrences of ! with the previous command when
             executing external commands.
         </p>
     </description>
@@ -641,7 +641,7 @@
             <dt>T</dt>      <dd>Toolbar</dd>
             <dt>b</dt>      <dd>Bottom scrollbar</dd>
             <dt>l</dt>      <dd>Left scrollbar (<em>l</em> and <em>r</em> are mutually exclusive)</dd>
-            <dt>m</dt>      <dd>Menubar</dd>
+            <dt>m</dt>      <dd>Menu bar</dd>
             <dt>n</dt>      <dd>Tab number</dd>
             <dt>r</dt>      <dd>Right scrollbar</dd>
         </dl>
@@ -682,7 +682,7 @@
         </p>
 
         <dl>
-            <dt>value</dt>      <dd>The hint is the value displayed in a text input, or the selected option for a dropdown.</dd>
+            <dt>value</dt>      <dd>The hint is the value displayed in a text input, or the selected option for a drop-down.</dd>
             <dt>label</dt>      <dd>The value of an explicit label for the input; this will not match most manually added labels that are found on sites.</dd>
             <dt>name </dt>      <dd>The name of the input will be used; although the name is not designed for user consumption, it is frequently very similar to the label.</dd>
         </dl>
@@ -742,7 +742,7 @@
             <dt>firstletters</dt>
             <dd>
                 Behaves like wordstartswith, but non-matching words
-                aren't overleaped.
+                aren't skipped.
             </dd>
             <dt>custom</dt>
             <dd>
@@ -1113,7 +1113,7 @@
     <tags>'previouspattern'</tags>
     <spec>'previouspattern'</spec>
     <type>stringlist</type>
-    <default><![CDATA[\bprev|previous\b,^<$,^(<<|«)$,^(<|«),(<|«)$]]></default>
+    <default><![CDATA['\bprev|previous\b',^<$,'^(<<|«)$','^(<|«)','(<|«)$']]></default>
     <description>
         <p>
             Patterns to use when guessing the previous page in a document
@@ -1552,7 +1552,7 @@
     <default><![CDATA[[.,!?:;\\/"^$%&?()[\]{}<>#*+|=~ _-]]]></default>
     <description>
         <p>
-            A regular expression which defines how words are split for the
+            A regular expression which defines how words are split for
             the <o>hintmatching</o> types <str>wordstartswith</str> and
             <str>firstletters</str>. Words are split on each occurrence of the
             given pattern.