Hi,
Thank you for your interest in Syncfusion Products.
Please refer the below link for online sample which illustrates of setting a Context Menu to a GridGroupingControl and opens a new window when Context Menu item is clicked using javascript. Also the sample files can be downloaded from 'Download source',
http://websamples.syncfusion.com/samples/Grid.Web/6.4.0.15/F78012-ContextMenu/main.htmPlease let me know if this sample helps you.
Thanks,
Rekha