Even though the page has enough space to display the left panel while you edit it, the panel is displayed under the buttons on a resized screen

Steps to reproduce:

1. Open your ie9 on VM
2. Click on Sandbox
3. See the Sandbox (has both panels in view mode, the left and the right ones)
4. Hover over "Edit" button
5. Select the WYSIWYG editor
6. You will see that the right Sandbox panels are displayed under the edited page