Note that the icons used in this example are provided in the ws sub-directory.

icodir←(2 ⎕NQ'.' 'GetEnvironment' 'Dyalog'),'\ws\'

'F'⎕WC'Form' 'TabControl: MultiLine Tabs, Justify None'('Size' 25 40)
'F.TC'⎕WC'TabControl'('MultiLine' 1)('Justify ' 'None')

'F.TC.IL'⎕WC'ImageList'
'F.TC.IL.'⎕WC'Icon'(icodir,'aplicon.ico')
'F.TC.IL.'⎕WC'Icon'(icodir,'funicon.ico')
'F.TC.IL.'⎕WC'Icon'(icodir,'editicon.ico')

'F.TC'⎕WS'ImageListObj' 'F.TC.IL'

'F.TC.T1'⎕WC'TabButton' 'First Tab'('ImageIndex' 1)
'F.TC.T2'⎕WC'TabButton' 'Second Tab'('ImageIndex' 2)
'F.TC.T3'⎕WC'TabButton' 'Third Tab'('ImageIndex' 3)
'F.TC.T4'⎕WC'TabButton' 'Fourth Tab'('ImageIndex' 1)