Duh: same for VS2013
It is still available, you just need to add it back to the View menu. Tools + Customize, Commands tab, Menu bar = View. Select the menu item in Controls where you want to insert it, say the bottom one. Then Add Command, Category = View, Commands = Tab Order.
Source: winforms – Where is the Tab Order Assignment dialog in Visual Studio 2012? – Stack Overflow
–jeroen





