Grouped headers are not supported at the moment by the DataGrid component.
I hope it is supported soon
This component looks like spreadsheet - we don’t have such component
I have one more question
I don't know why when I click on textbox and combobox on the grid, it's very slow
just 10records / page
Maybe the performance problem was caused by the fact that you have populated a lot of DropDown components for every cell in some of the grid columns. Editing single cell/row will be much more performant in my opinion.