its very easy to add tooltip to icon's
1) have a icon field in output table ( this can be a char field with 25 characters)
2) in case if you cant to add the lock icon for that icon field put
in this @06@ is the icon when you give the tooltip with '\QXXXtooltipXXX'
insert this part beore last @.
Note: if you want to find the icons check icon table :)
3) field catalog make the icon field 'X'.
there is a SAP example on program: BCALV_DEMO_TOOLTIP