This setting OPTIONS=NOWHEEL disables the otherwise automatic conversion of the mouse wheel events into Up/Down-Arrow key presses when the focus is not on a control that captures the mouse wheel directly (such as XTREE, multi-line INFLD, etc.).

The default behavior allows you to use the mouse wheel to scroll within certain environments that are otherwise text-only (like VUE). But in some cases the default behavior is undesirable, for example:

•   On laptops with sensitive mouse pads, you may get spurious cursor motion just from brushing your palm against it (very annoying in VUE).

•   In screen contexts where there may be a mixture of controls that scroll (like XTREE) and those that don't (like a single line INFLD), users may attempt to use the mouse wheel with the intent to scroll an object like XTREE, when in fact the focus is on a control like INFLD where the conversion of the mouse wheel to an Up/Down-Arrow may trigger unwanted exitcodes (3 & 5), leading to further confusion.

Note that VUE supports its own version of this switch (in the ini.vue and command mode) MOUSEPOS<boolean>, which see for information on the relationship of this setting and that one.

Also, the mouse wheel is disabled in INFLD self-combo fields (which exit on the first down arrow key); otherwise it is too easy to end up with several additional down arrow key events which would then be interpreted according to logic impossible for the user to predict. Self-combos within XTREE continue to operate as before.

History

2020 June, A-Shell 6.5.1681:  NOWHEEL now also disables the mouse wheel within a combo box field.