Steps to reproduce:

go to https://www.zkoss.org/zkdemo/listbox/dual_listbox

On the listbox : Have the first entry selected, then press Ctrl + Left Click on another entry.
=> It applies a selection to the text label as well.
Expected : only clicked listitem gets added to selection

On the listbox : click an entry to select it (1st click), then press Shift + Left Click on another entry.
=> It applies text selection on all the text content from the 1st click location upward until the listbox header.
Expected : only the listitems range between 1st click and 2nd click gets selected