CreateDocument[{
  DynamicModule[{x = 100}, {
    Grid[{{
       	TextCell@"Choose Distribution:",
       		PopupMenu[
        Dynamic@dist, {NormalDistribution -> Normal,
         PoissonDistribution -> Poisson}]
       },
      	{TextCell@"Number of samples:",
       	InputField[Dynamic[x], Number, ImageSize -> 100]
       }
      }
     ],
    }
   ],
  Button["Buton", Histogram[RandomVariate[dist[1, 3], x]]]
  }
 ]