Thank you BIGAL.
I'm pleased with the results, although I am still 'polishing'
I managed to achieve having all of the drawing numbers/names and the slides in the text file:
("LD-200mm RH Reducer" "LD-200mm-tray-Reducer-3000" "ldct5-r.sld")
where
"LD-200mm RH Reducer" is the text displayed in the list box
"LD-200mm-tray-Reducer-3000" is the drawing number/name
"ldct5-r.sld" is the slide displayed in the 'preview' image
And whilst this is probably food & drink to most of the posters here, it was more difficult for me.
This means that I can add new blocks to the lists without having to modify the lsp file. I still do not have the full set of blocks.
Or change the slides to individual rather than 'generic' ones.
The next project will include radio buttons and possibly 'concatenated' drawing numbers, and slides with generic dimension (ie 'A' 'B' 'C'...) and then a display of the actual dimensions, a bit like a catalogue. Again I hope to include the dimensions in the txt file so they will be n3, n4, n5........
.