The button create activity control will bring forward the the schedule activity window from ACT.
The default code is
'--------------------------------------------------
' Attach a file
'--------------------------------------------------
Dim aActivityType As ACT.Framework.Activities.ActivityType = HostFramework.Activities.GetActivityType(0)
HostApplication.UIActivityManager.ScheduleNewActivity(aActivityType)
To change the default code, click the ellipses (...) button in the properties panel, change the code and click save.