Oracle Forms

Hello All,
I am using a Text Item and a List Box in a form having following basic properties set as,

Text Box porperties
Item Type = Text Item
Multi-line = Yes
Maximum Length =32000

List Box properties
Item Type = List Item
List Style = Tlist
Data type = Char

I have set some list values(Element in list) for the list box viz. 'tag1','tag2','tag3' etc
What I want is
when I doubleclick on the List box on any label the value for that label index should get inserted at the cursor position in the Text Box.
i.e If the text is like this

' Your account no is and your opening balance is'

then if I place the cursor in the text box after 'account no' and doubleclik on the list box label 'tag1' then it should insert 'tag1' at cursor position in the text box.
i.e. the new text should be

'Your account no is 'tag1' and your opening balance is'

Till now I am able to append the selected tag to the text in the text box but, am unble to insert the tags at the cursor position.

Can anybody help me?

Regards,