I have several scripts with date inputfields. We have been successfully using the option searchhelp="GuiXT.DATE" as shown below with earlier versions of GuiXT, specifically 2011 Q1 3.
inputfield (0,0) "Date of Work" (0,15) name="iw_noti_lro_dateofwork" -date -numerical searchhelp="GuiXT.DATE"
I've just begun testing GuiXT version 2012 Q3 2 and ran into the situation where no calendar is popped up when the user clicks the searchelp for the field (or presses F4 in the field).
This is occurring with both SAPGui 7.10 and SAPGui 7.30 (we never adopted SAPGui 7.20).