2.4.1 Calling procedure for modal dialogs

wind_update()           Lock screen
lbox_create()           Create list box
form_center()           Centre dialog
form_dial()             Buffer screen portion
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Loop:       form_do() <----
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            lbox_do() -----

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End of loop (e.g. OK or Cancel activated)
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Possibly lbox_get_slct_item()...
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form_dial()             Send redraw message
wind_update()           Release screen
lbox_delete()           Release memory for list box