2 that are currently bugging me are to do with the Dialog List 'control' and, in particluar, the styles size and extsel,

Both are mentioned in mIRC Help as far as their existance -
'list id, x y w h, style (sort, extsel, multsel, size, vsbar, hsbar, check, radio)'

but no explation.

WikiChip has extsel with -
'Allows extra selection support',
but nothing further. What extra selction support ?

So what do they do ?