Ok, I tried this, and I'm getting incorrect results.

I have a cursor with 2 columns, ID and Caption. Their widths are 4 & 50.

sColWidths = "0,"
sFontName = .lstAssigned.FontName
iFontSize = .lstAssigned.FontSize

FOR iColumn = 1 TO FCOUNT()
  iSize = TXTWIDTH(ALLTRIM(FIELD(iColumn)), sFontName, iFontSize)
  sColWidths = sColWidths + TRANSFORM(CEILING(iSize)) + ","
ENDFOR

This results in sColWidths being "0,2,10,"






>>I need to load a list box in a SCAN/ENDSCAN.
>>
>>Some columns may or may not be visible, so I want to set the ColumnWidths property
>>from the data.
>>
>>How do I calculate the ListBox ColumnWidth? I could use FONTMETRIC(6,,) * FSIZE(), but that
>>would result in some really wide columns in the listbox.
>
>You could calculate max(txtwidth(alltrim(yourfield), listbox.fontname, listbox.fontsize, "N"), that would give you a pretty good estimate. Add a few pixels for margin.