Fix sidebar not resizable when set to show/hide automatically

Fixes #592.

assets/javascripts/views/sidebar/sidebar.coffee

@@ -27,11 +27,11 @@ class app.views.Sidebar extends app.View
     return
 
   display: ->
-    @el.style.display = 'block'
+    @addClass 'show'
     return
 
   resetDisplay: ->
-    @el.style.display = '' unless @el.style.display is 'none'
+    @removeClass 'show'
     return
 
   showView: (view) ->

assets/stylesheets/components/_sidebar.scss

@@ -40,9 +40,8 @@
     }
   }
 
-  ._sidebar-hidden & {
-    display: none;
-  }
+  ._sidebar-hidden & { display: none; }
+  &.show { display: block; }
 }
 
 ._resizer {
@@ -56,6 +55,7 @@
   cursor: col-resize;
 
   ._sidebar-hidden & { display: none; }
+  ._sidebar-hidden ._sidebar.show ~ & { display: block; }
 }
 
 //