[Libreoffice] How to make cell with list data validation, a combo box

Hello,

I've been trying to make a combobox for a cell with Data Validation > List
for LibreOffice calc.

I thought I could add that in the source and try out - so I downloaded LO
source and started greping for text, all thanks to the excellant LO page to
do so and the LibreOffice IRC channel.

Now, for days I've been grepping the source for texts that I could think of,
with no success. I open loads of *.cxx file and I'm not able to make out
where this code lies.

Can anyone help me with a better approach to find this piece of code that
shows selection list for a cell with "List" data validity?

Thanks in Advance
Kishan