4.7 Dynamically change the layout of Manipulate

Manipulate[x, 
 
 {x, {True, False}}, 
 Grid[{ 
   {Dynamic@If[x, 
      Control[{y, {True, False}}], 
      Control[{z, 0, 1, .1}] 
      ] 
    } 
   } 
  ] 
 ]