Change IE meta tag from "IE=8" to "IE=9"

• In a document library, the “Send To” option in the context menu doesn’t doesn’t display the secondary menu

• Rich text editor fields in dialog boxes do not allow text entry.

 

• Save button in dialog boxes do not work.

• The people picker save button is disabled.
• Web Parts cannot be moved from zone to zone, they go back to their default location when you stop editing the page
• Site Permissions > Create a New Group (newgrp.aspx) page wont submit. The Rich Text entry box for the new group ‘About Me’ is greyed out. The page errors out in Office365
• Instant Messaging presence pawn is broken
• Event in calendar view can’t postback/create an item
• The mini calendars within the Modal Popup Dialog Box when the Week Day is enabled (“Show week numbers”…); the design for the calendar crashes
• Lookup fields with 20+ items will not display the dropdown list
• People Picker is broken

 

Reference : http://blog.sharepointexperience.com/2012/07/convert-sharepoint-2010-master-page-html5/