Hi Imran,
Thank you for your patience.
You need to handle BeforePopup event of DropDownContainer in the DropDownCellRenderer class and set the PopHost.FormBorderStyle property to FormBorderStyles other than Sizable and SizableToolWindow, to stop resizing the DropDownContainer. Please refer the sample code for more details.
void DropDownContainer_BeforePopup(object sender, System.ComponentModel.CancelEventArgs e)
{
this.DropDownContainer.PopupHost.FormBorderStyle = FormBorderStyle.None;
}
Here is the minimal sample which implements this task.
http://websamples.syncfusion.com/samples/grid.windows/F73379/main.htmPlease let me know if this helps.
Best Regards,
Srirajan