diff --git a/addons/account/account_view.xml b/addons/account/account_view.xml
index b0dbb55bd51..623fef0662f 100644
--- a/addons/account/account_view.xml
+++ b/addons/account/account_view.xml
@@ -600,7 +600,7 @@
                     <notebook>
                         <page string="Transactions" name="statement_line_ids">
                             <field name="line_ids" context="{'date':date}">
-                                <tree editable="bottom" string="Statement lines">
+                                <tree editable="bottom" string="Statement lines" colors="grey:journal_entry_ids">
                                     <field name="sequence" readonly="1" invisible="1"/>
                                     <field name="journal_entry_ids" invisible="1"/>
                                     <field name="date" attrs="{'readonly' : [('journal_entry_ids', '!=', [])] }"/>
diff --git a/addons/account_bank_statement_extensions/account_bank_statement_view.xml b/addons/account_bank_statement_extensions/account_bank_statement_view.xml
index f0796b4631d..d546c49f6b1 100644
--- a/addons/account_bank_statement_extensions/account_bank_statement_view.xml
+++ b/addons/account_bank_statement_extensions/account_bank_statement_view.xml
@@ -57,7 +57,7 @@
       <field name="name">bank.statement.line.list</field>
       <field name="model">account.bank.statement.line</field>
       <field name="arch" type="xml">
-        <tree editable="bottom" string="Statement Lines">
+        <tree editable="bottom" string="Statement Lines" colors="blue:not journal_entry_ids">
           <field name="sequence" readonly="1" invisible="1"/>
           <field name="journal_id" readonly="1"/>
           <field name="date" readonly="1"/>
diff --git a/addons/l10n_be_coda/l10n_be_coda_view.xml b/addons/l10n_be_coda/l10n_be_coda_view.xml
index 6983bc15790..079b63d643b 100644
--- a/addons/l10n_be_coda/l10n_be_coda_view.xml
+++ b/addons/l10n_be_coda/l10n_be_coda_view.xml
@@ -38,7 +38,7 @@
             <field name="model">account.bank.statement.line</field>
             <field name="priority">10</field>
             <field name="arch" type="xml">
-                <tree editable="bottom" string="Statement lines" create="0">
+                <tree editable="bottom" string="Statement lines" create="0" colors="blue:not journal_entry_ids">
                     <field name="sequence" readonly="1" invisible="1"/>
                     <field name="statement_id" readonly="1" />
                     <field name="date"/>
@@ -86,4 +86,4 @@
 
         <menuitem name="Bank Statement Lines" parent="account.menu_finance_bank_and_cash" id="menu_account_bank_statement_line_coda" action="action_account_bank_statement_line_coda" sequence="8" groups="base.group_no_one"/>
 	</data> 
-</openerp>
\ No newline at end of file
+</openerp>
diff --git a/addons/web/static/lib/py.js/README.rst b/addons/web/static/lib/py.js/README.rst
index 7601318df6d..5380f3e6c8f 100644
--- a/addons/web/static/lib/py.js/README.rst
+++ b/addons/web/static/lib/py.js/README.rst
@@ -53,7 +53,7 @@ Builtins
     Same as tuple (``list`` is currently an alias for ``tuple``)
 
 ``dict``
-    Implements trivial getting and setting, nothing beyond that.
+    Implements trivial getting, setting and len, nothing beyond that.
 
 Note that most methods are probably missing from all of these.
 
diff --git a/addons/web/static/lib/py.js/TODO.rst b/addons/web/static/lib/py.js/TODO.rst
index a1309bd3fc5..dd3237e3572 100644
--- a/addons/web/static/lib/py.js/TODO.rst
+++ b/addons/web/static/lib/py.js/TODO.rst
@@ -35,7 +35,6 @@ Base methods requirement
 
 * ``__getattr__``
 * ``dict.get``
-* ``__len__``
 
 In datamodel, not implemented in any type, untested
 ***************************************************
diff --git a/addons/web/static/lib/py.js/lib/py.js b/addons/web/static/lib/py.js/lib/py.js
index 2c738dc95d1..2c6c832f9fe 100644
--- a/addons/web/static/lib/py.js/lib/py.js
+++ b/addons/web/static/lib/py.js/lib/py.js
@@ -320,7 +320,7 @@ var py = {};
                     if (token === 'in' && tokens[tokens.length-1].id === 'not') {
                         symbol = symbols['not in'];
                         tokens.pop();
-                    } else if (token === 'not' && tokens[tokens.length-1].id === 'is') {
+                    } else if (token === 'not' && tokens.length > 0 && tokens[tokens.length-1].id === 'is') {
                         symbol = symbols['is not'];
                         tokens.pop();
                     } else {
@@ -969,6 +969,12 @@ var py = {};
         __init__: function () {
             this._values = [];
         },
+        __len__: function () {
+            return this._values.length;
+        },
+        __nonzero__: function () {
+            return py.PY_size(this) > 0 ? py.True : py.False;
+        },
         __contains__: function (value) {
             for(var i=0, len=this._values.length; i<len; ++i) {
                 if (py.PY_isTrue(this._values[i].__eq__(value))) {
@@ -1013,6 +1019,12 @@ var py = {};
         __setitem__: function (key, value) {
             this._store[key.__hash__()] = [key, value];
         },
+        __len__: function () {
+            return Object.keys(this._store).length
+        },
+        __nonzero__: function () {
+            return py.PY_size(this) > 0 ? py.True : py.False;
+        },
         get: function () {
             var args = py.PY_parseArgs(arguments, ['k', ['d', py.None]]);
             var h = args.k.__hash__();
diff --git a/addons/web/static/src/js/view_list.js b/addons/web/static/src/js/view_list.js
index 0e446fb323e..135f73d2ce2 100644
--- a/addons/web/static/src/js/view_list.js
+++ b/addons/web/static/src/js/view_list.js
@@ -182,7 +182,7 @@ instance.web.ListView = instance.web.View.extend( /** @lends instance.web.ListVi
                 pair = this.fonts[i];
                 var font = pair[0];
                 expression = pair[1];
-                if (py.evaluate(expression, context).toJSON()) {
+                if (py.PY_isTrue(py.evaluate(expression, context))) {
                     switch(font) {
                     case 'bold':
                         style += 'font-weight: bold;';
@@ -203,7 +203,7 @@ instance.web.ListView = instance.web.View.extend( /** @lends instance.web.ListVi
             pair = this.colors[i];
             var color = pair[0];
             expression = pair[1];
-            if (py.evaluate(expression, context).toJSON()) {
+            if (py.PY_isTrue(py.evaluate(expression, context))) {
                 return style += 'color: ' + color + ';';
             }
             // TODO: handle evaluation errors
diff --git a/addons/web/static/src/js/view_tree.js b/addons/web/static/src/js/view_tree.js
index aac7198f2c3..45cc183511a 100644
--- a/addons/web/static/src/js/view_tree.js
+++ b/addons/web/static/src/js/view_tree.js
@@ -145,7 +145,7 @@ instance.web.TreeView = instance.web.View.extend(/** @lends instance.web.TreeVie
             var pair = this.colors[i],
                 color = pair[0],
                 expression = pair[1];
-            if (py.evaluate(expression, context).toJSON()) {
+            if (py.PY_isTrue(py.evaluate(expression, context))) {
                 return 'color: ' + color + ';';
             }
             // TODO: handle evaluation errors