date selection control in header cell is not supported, but it can be added in 1st row with help of column.render callback.
postRenderInterval: -1,
colModel:[{
dataIndx: 'rank',
render: function(ui){
if(ui.rowIndx==0)
return "<input type='date' />";
},
postRender: function(ui){
var grid = this;
$(ui.cell).find('input').on('change', function(){
alert("do stuff");
});
}
},