Hi Shayesteh,
Thanks for your interest in Syncfusion products.
This feature can be achieved by means of two event handlers in gridcontrol: CurrentCellShowingDropDown and CurrentCellCloseDropDown.
Please refer the following sample to achieve this feature.
http://websamples.syncfusion.com//samples/Grid.Windows/F77340/main.htmPlease let me know if this helps.
Regards,
Rajadurai