Dear Zhaonjie,
At the moment the core widget widget shipped with the modeler are not fully “pluggable” and can not be copied and or extended.
Beside the core widgets are not open source. I would love to see this happening in the future.
Unfortunately you have to start from a new. Luck with the tooling https://docs.mendix.com/howto/extensibility/pluggable-widgets you can quickly scaffold a new widget and with the other public repos https://github.com/mendix/widgets-resources you might get to your goal quickly.
Cheers, Andries