This configuration variable applies only to programs running under Windows.
If WIN_F4_DROPS_COMBOBOX is set to its default value of 1 (on, true, yes), then combo boxes use the standard Windows handling for the <F4> key. Pressing <F4> while a combo box is active causes it to drop its drop-down list, and the COBOL program is not notified of an exception.
When this variable is set to 0 (off, false, no), pressing <F4> with a combo box active causes the COBOL program to get the exception, but the combo box does not drop its drop-down list.
It is not possible to get both behaviors at the same time.