Hi Narendra,
Sorry for the inconvenience caused. This is a known issue in v.3.3.0.0 which has been fixed in v.4.1.0.50 and our later releases.
Defect #666 - ComboBoxBarItem Editable property does not make ComboBoxBarItem editable.
You can download v.4.2.(latest release) from the following link:
http://www2.syncfusion.com/Installs/v4.2.0.37/syncfusionessentialstudiosetup.exe
UnlockKey : Please contact our sales team(salessupport@syncfusion.com) to get an unlock key for this version.
Thanks for using Syncfusion products.
Regards,
J.Nagaraj