@@ -219,6 +219,8 @@ The main customization for the homepage is to display either the reports
 * `NORMALIZATION`: Defines whether normalization should be enabled as default
   in the Comparison view.
 * `CHART_ORIENTATION`: horizontal or vertical
+* `COMP_ENVIRONMENTS_DEFAULT`: `all` (the default) checks every environment;
+  `default` checks only `DEF_ENVIRONMENT`, or the first environment.
 * `COMP_EXECUTABLES`: per default all executables will be checked. When there
   are a large number of tags or executables, it is better to only select a few
   so that the plots are not too cluttered.
 
@@ -50,6 +50,10 @@
                           # undeseriable.
 
 TIMELINE_GRID_PAGING = 4   # Number of benchmarks to be send in one grid request
+
+TIMELINE_GRID_REVISIONS = None  # Number of revisions plotted per benchmark in the
+                                # timeline grid. None keeps the count selected in
+                                # the "Show the last" dropdown.
                            # May be adjusted to improve the performance of the timeline grid view.
                            # If a large number of benchmarks is in the system,
                            # and the database is not fast, it can take a long time
@@ -69,6 +73,10 @@
 CHART_ORIENTATION = 'vertical' # 'vertical' or 'horizontal can be chosen as
                               # default chart orientation
 
+COMP_ENVIRONMENTS_DEFAULT = 'all'  # Environments checked by default on the comparison
+                                   # page: 'all', or 'default' for DEF_ENVIRONMENT only
+                                   # (falling back to the first environment)
+
 COMP_EXECUTABLES = None  # Which executable + revision should be checked as default
                          # Given as a list of tuples containing the
                          # name of an executable + commitid of a revision
 
@@ -482,6 +482,10 @@ function init(defaults) {
         updateBaselineDropdown();
         refreshContent();
     });
+    $("#environment .checkall, #environment .uncheckall").click(function() {
+        updateBaselineDropdown();
+        refreshContent();
+    });
 
     $.ajaxSetup ({
       cache: false
 
@@ -554,7 +554,10 @@ function render(data) {
             config.nextBenchmarks = data.nextBenchmarks;
             $.getJSON("json/", config, render);
         }
-        $("#revisions").val(15).attr("disabled", true);
+        if (defaults.grid_revisions) {
+            $("#revisions").val(defaults.grid_revisions);
+        }
+        $("#revisions").attr("disabled", true);
         $("#equidistant").attr("disabled", true);
         for (var i = 0; i < data.timelines.length; i++) {
             var tl = data.timelines[i];
 
@@ -15,12 +15,13 @@
 
 {% block body %}
 <div id="sidebar">
-<div class="sidebox">
+<div id="environment" class="sidebox">
   <div class="boxhead"><h2>Environments</h2></div>
   <div class="boxbody">
-    <ul>{% for env in enviros %}
+    <ul><a href="#" class="togglefold">Environments</a> <span class="checklinks">(<a href="#" class="checkall">All</a>, <a href="#" class="uncheckall">None</a>)</span>
+    {% for env in enviros %}
       <li title="{{ env.os }}, {{ env.cpu }}">
-        <input id="env_{{ env.id }}" type="checkbox" name="environments" value="{{ env.id }}" />
+        <input id="env_{{ env.id }}" type="checkbox" name="environments" value="{{ env.id }}"{% if env in checkedenviros %} checked{% endif %} />
         <label for="env_{{ env.id }}">{{ env }}</label>
       </li>{% endfor %}
     </ul>
@@ -93,10 +94,6 @@
 <script type="text/javascript" src="{% static 'js/comparison.js' %}"></script>
 
 <script type="text/javascript">
-  var checkboxes = document.getElementsByTagName('environments');
-  for (c in checkboxes) {
-    c.checked = false;
-  }
   $(function() {
     Comparison.init({
       chart_type: "{{ selectedchart }}",
 
@@ -67,7 +67,7 @@
   </ul>{% endif %}
   {% regroup benchmarks by get_source_display as benchmark_groups %}
   {% for group in benchmark_groups %}
-  <ul><a href="#" class="togglefold">{{ group.grouper }}</a>
+  <ul>{% if benchmark_groups|length > 1 %}<a href="#" class="togglefold">{{ group.grouper }}</a>{% endif %}
     {% for bench in group.list|dictsort:"name" %}
     <li title="{{ bench.description }}">
       <input id="benchmark_{{ bench.id }}" type="radio" name="benchmark" value="{{ bench.ident }}" />
@@ -120,6 +120,7 @@
   $(function() {
     Timeline.init({
       revisions: {{ defaultlast }},
+      grid_revisions: {{ grid_revisions|default_if_none:"null" }},
       baseline: "{{ defaultbaseline }}",
       executables: [{% for exe in checkedexecutables %}{{ exe.id }}, {% endfor %}],
       branches: [{% for b in branch_list %}"{{ branch }}", {% endfor %}],
 
@@ -455,6 +455,67 @@ def test_gettimelinedata(self):
             responsedata['timelines'][0]['branches']['master']['1:1'][1],
             [u'2011/04/13 17:04:22 +0000', 2000.0, 1.11111, u'2', u'', u'master', u''])
 
+    def test_no_source_fold_with_one_source(self):
+        """A single source shows a flat benchmark list and no fold header"""
+        response = self.client.get(reverse('timeline'))
+        self.assertEqual(response.status_code, 200)
+        self.assertIsNone(response.context['grid_revisions'])
+        self.assertNotContains(response, 'class="togglefold">Legacy</a>')
+        self.assertContains(response, 'grid_revisions: null')
+
+    def test_source_fold_with_several_sources(self):
+        Benchmark.objects.create(name='float', source='pyperformance')
+        response = self.client.get(reverse('timeline'))
+        self.assertContains(response, 'class="togglefold">Legacy</a>')
+        self.assertContains(response, 'class="togglefold">PyPerformance</a>')
+
+    @override_settings(TIMELINE_GRID_REVISIONS=25)
+    def test_grid_revisions_setting(self):
+        response = self.client.get(reverse('timeline'))
+        self.assertEqual(response.context['grid_revisions'], 25)
+        self.assertIn(25, response.context['lastrevisions'])
+        self.assertContains(response, 'grid_revisions: 25')
+
+
+class TestComparison(TestCase):
+    fixtures = ["timeline_tests.json"]
+
+    def setUp(self):
+        self.path = reverse('comparison')
+        self.dual = Environment.objects.get(name='Dual Core')
+        self.quad = Environment.objects.create(name='Quad Core')
+
+    def checked_env_names(self, response):
+        return sorted(e.name for e in response.context['checkedenviros'])
+
+    def test_all_environments_checked_by_default(self):
+        response = self.client.get(self.path)
+        self.assertEqual(response.status_code, 200)
+        self.assertEqual(self.checked_env_names(response),
+                         ['Dual Core', 'Quad Core'])
+
+    @override_settings(COMP_ENVIRONMENTS_DEFAULT='default',
+                       DEF_ENVIRONMENT='Quad Core')
+    def test_only_default_environment_checked(self):
+        response = self.client.get(self.path)
+        self.assertEqual(self.checked_env_names(response), ['Quad Core'])
+        # Permalinks still select several environments
+        response = self.client.get(
+            self.path, {'env': '%d,%d' % (self.dual.id, self.quad.id)})
+        self.assertEqual(self.checked_env_names(response),
+                         ['Dual Core', 'Quad Core'])
+
+    def test_benchmarks_grouped_by_units_with_one_source(self):
+        response = self.client.get(self.path)
+        self.assertEqual(list(response.context['benchmarks']), ['Time'])
+        self.assertContains(response, 'class="togglefold">Time</a>')
+
+    def test_benchmarks_grouped_by_source_with_several_sources(self):
+        Benchmark.objects.create(name='float', source='pyperformance')
+        response = self.client.get(self.path)
+        self.assertEqual(list(response.context['benchmarks']),
+                         ['Legacy', 'PyPerformance'])
+
 
 @override_settings(ALLOW_ANONYMOUS_POST=True)
 class TestReports(TestCase):
 
@@ -326,7 +326,10 @@ def comparison(request):
     enviros = Environment.objects.all()
     if not enviros:
         return no_environment_error(request)
-    checkedenviros = get_default_environment(enviros, data)
+    checkedenviros = get_default_environment(enviros, data, multi=True)
+    if 'env' not in data and \
+            get_setting('COMP_ENVIRONMENTS_DEFAULT', 'all') == 'default':
+        checkedenviros = get_default_environment(enviros, data)
 
     if not len(Project.objects.filter(track=True)):
         return no_default_project_error(request)
@@ -395,13 +398,18 @@ def comparison(request):
 
     benchmarks = {}
     bench_units = {}
-    for source_val, source_label in Benchmark.S_TYPES:
+    sources = [(val, label) for val, label in Benchmark.S_TYPES
+               if Benchmark.objects.filter(source=val).exists()]
+    # Sidebar groups: by source when there are several, else by units title
+    group_by_source = len(sources) > 1
+    for source_val, source_label in sources:
         qs = Benchmark.objects.filter(source=source_val)
-        if not qs.exists():
-            continue
-        benchmarks[source_label] = qs
+        if group_by_source:
+            benchmarks[source_label] = qs
         for unit in qs.values_list('units_title', flat=True).distinct():
             unit_qs = qs.filter(units_title=unit)
+            if not group_by_source:
+                benchmarks[unit] = unit_qs
             units = unit_qs[0].units
             lessisbetter = (unit_qs[0].lessisbetter and
                             ' (less is better)' or ' (more is better)')
@@ -806,6 +814,9 @@ def timeline(request):
     for proj in Project.objects.filter(track=True):
         executables[proj] = Executable.objects.filter(project=proj)
     use_median_bands = hasattr(settings, 'USE_MEDIAN_BANDS') and settings.USE_MEDIAN_BANDS
+    grid_revisions = get_setting('TIMELINE_GRID_REVISIONS', None)
+    if grid_revisions and grid_revisions not in lastrevisions:
+        lastrevisions = sorted(lastrevisions + [grid_revisions])
     if isinstance(defaultbenchmark, Benchmark):
         defaultbenchmark_value = defaultbenchmark.ident()
     else:
@@ -821,6 +832,7 @@ def timeline(request):
         'defaultenvironments': defaultenvironments,
         'lastrevisions': lastrevisions,
         'defaultlast': defaultlast,
+        'grid_revisions': grid_revisions,
         'executables': executables,
         'benchmarks': benchmarks,
         'environments': enviros,
 
@@ -100,6 +100,8 @@
 DEF_ENVIRONMENT = 'benchmarker2'
 CHART_ORIENTATION = 'horizontal'
 DEF_BENCHMARK = 'grid'
+TIMELINE_GRID_REVISIONS = 15
+COMP_ENVIRONMENTS_DEFAULT = 'default'
 
 
 from .local_settings import *