Under certain conditions the column width in a listbox gets set wrong using the explicit width="" and also using vflex="min".
There are two problems (it also happens under other conditions, but propably it's all the same bug) which are shown in following fiddle:

http://zkfiddle.org/sample/2vo58c8/5-listbox-column-width-wrong

• first issue:
  1. In the first listbox, first the Column width are set right.
  2. Then, when you click on the checkbox at the top, some of the columns are made invisible, and other visible.
  3. the width is still right
  4. then click again on the checkbox, to make the previous columns visible
  5. now the column widths are completely wrong.
  6. click several times again on the checkbox, the column widths will change each time.

• 2nd issue
  1. in the second listbox, two columns width are not defined, but vflex="min" is used
  2. if the listbox only contains one line, everything is correct
  3. if the listbox contains a lot of lines, like in the example. It first seems like everything is correct, but if you wait a few seconds, at once the column width will be reset. (propably after some rendering task ends)