WebListBox.ColumnWidths
From Xojo Documentation
or
StringValue = aWebListBox.ColumnWidths
New in 2010r4
Supported for all project types and targets.
A list of comma separated values, with each value controlling the width of the associated column. A value can be an absolute value (in pixels), a percentage, a relative length expressed as "i*" where i is an integer, or an "*" that indicates "fill in the remaining width". If you use percentages, you can use non-integer values to specify fractions of a percent, e.g., 43.52%. The percentage value can be greater than 100%.
Notes
If you use pixels, the last column doesn't grow to the size of the rest of the ListBox. You should set the width of the last column to "*" and it will automatically take up the remaining width of the ListBox.
Without any column width specifications, the headers will be divided evenly. If there are fewer column widths specified than the total number of columns, the remaining columns will divide up the remaining width equally.
Examples
The following creates two columns with 100 pixels per column:
The following uses the * to specify the last column's width: