I have seen example where this was done using a picture control. No, I don't believe this could done using a graph control. Using an XY graph you could add a circle but probably not using the mouse. Use other controls like radius on location to move is around.
Matt Fitzsimons
NI Alliance Member
LabVIEW Champion
NI Certified LabVIEW Architect
LabVIEW, LV-RT, Vision, DAQ, Motion, and FPGA