Add show all vs. show diffs for upgrade packages

plus some related tweaks

tailbone/views/upgrades.py

@@ -40,7 +40,7 @@ from rattail.threads import Thread
 from rattail.upgrades import get_upgrade_handler
 
 from deform import widget as dfwidget
-from webhelpers2.html import tags
+from webhelpers2.html import tags, HTML
 
 from tailbone.views import MasterView3 as MasterView
 from tailbone.progress import SessionProgress, get_progress_session
@@ -206,7 +206,13 @@ class UpgradeView(MasterView):
                                   columns=["package", "old version", "new version"],
                                   render_value=self.render_diff_value,
             )
-            return diff.render_html()
+            showing = HTML.tag('div',
+                               "showing: "
+                               + tags.link_to("all", '#', class_='all')
+                               + " / "
+                               + tags.link_to("diffs only", '#', class_='diffs'),
+                               class_='showing')
+            return showing + diff.render_html()
         except:
             return "(not available for this upgrade)"