How do you create two grid columns like the Entry Edit page within a plugin?
templates/layouts/_cp.html has 

&lt;div class="grid"&gt;
  &lt;div class="item"&gt;
    &lt;div class="pane"&gt;


nested inside the {% block main %} (line  207) and templates/entries/_edit.html is overriding that block main, so those grid,item,pane divs get overridden too.