Cursor position in a combobox

[sunaj]

Hi,

I'm made a small facility that helps me contruct select statements. It consists of 3 comboboxes:
1 with the Tablenames, 1 with the fieldnames and one for the select statement. When I select a Table or field name I want the program to insert the name in the third combobox AT THE CURSOR POSITION. My question is:

How do I get the cursor posistion in the combobox (I tried with .selstart, but it dosen't work...)

Thanks,
Sunaj