Is it possible to use WinEditor in WinGrid? For example, if user click a cell in a particular column, I want to pop up a WinCalculatorDropDown.
If it is possble, mind providing a brief idea on how to do it in code?
This documentation might be of use to you. The WinGrid is so amazingly flexible, that you can do pretty much everything with it!
That article is for non-editor controls. It'sfar more complicated than you need here.
All you need to do in this case is place an UltraCalculatorDropDown control on the form with the grid and set the grid column's EditorControl property to the calculator dropdown control.