Edit the page in Advanced Mode from Sharepoint Designer is greyed out.

Edit the page in Advanced Mode from Sharepoint Designer is greyed out.

This blog describes another practical scenario where you are not able to edit the sharepoint page in Advanced mode from SharePoint Designer 2010. 
 
Issue :
 
Not able to Edit the Advance Mode From SharePoint Designer 2010 
 
Resolution :
 
1.http://site-name/_layouts/15/SharePointDesignerSettings.aspx is the page you need to work on. 
 
2.To access  the page , Go to Central Administration.
 
       a. Central Administration - Web Applications- Manage Web Applications - Select the Web Application.
        b. From Ribbon Navigate to Manage >General Settings > SharePoint Designer.
 
3. In the SharePoint Designer section, Check the  "Enable Detaching Pages from the Site Definition".
 
That's it folks. The Page can be easily edited now. 
 
Happy SharePointing :-)