IMPR: Allow to disable sidebar

src/Extensions/SiteTreeExtension.php

@@ -49,6 +49,11 @@ class SiteTreeExtension extends DataExtension
     public function ShowSidebar()
     {
         $obj = $this->owner;
+
+        if($obj->DisableSidebar) {
+            return false;
+        }
+
         $area = $obj->ElementalArea();
         if (!$area) {
             return true;

templates/Includes/MainContent.ss

@@ -7,7 +7,7 @@
         </div>
     <% end_if %>
 
-    <% if not $DisableSidebar && $SideBarContent || $SideBarView && $SideBarView.Widgets.Count %>
+    <% if $ShowSidebar %>
         <div class="content-holder content-holder__sidebar">
             <div class="{$DefaultContainer}">
                 <div class="row">