shift-click system tray icon

Anyone know how to require a shift-right click on the script icon in the system tray to make it do something?  I want it to require a shift-right click to trigger an action.
 
I have it working with a right click but dont know how to require the shift key at the same time. 

#include <TrayConstants.au3> 

Opt("TrayMenuMode", 3)

TraySetState($TRAY_ICONSTATE_SHOW) 

While 1
    Switch TrayGetMsg()
        Case $TRAY_EVENT_SECONDARYDOWN
            msgbox(0,"","test")
        ExitLoop
    EndSwitch
WEnd