sss= """item a
item b
item c
item d
"""
ss= sss.splitlines()
# Or ss= listDirectory('http://autoplot.org/data/agg/hyd/2000/*.cdf')

from javax.swing import JPanel
from javax.swing import JCheckBox
from javax.swing import BoxLayout
from javax.swing import JDialog
from javax.swing import JScrollPane

p= JPanel()
p.setLayout( BoxLayout( p, BoxLayout.Y_AXIS ) )

for s in ss:
    p.add( JCheckBox(s) )
    
jd= JDialog()
jsp= JScrollPane(p)
jd.getContentPane().add(jsp)
jd.pack()
jd.setLocationRelativeTo( getViewWindow() )
jd.setVisible(True)