Clear search form when selecting “All makes” option

Hi,

I have noticed that when using the search form, selecting the “All makes” option in the brands drop-down does not clear the “model” field, as it does when selecting any other brand.

I am using the following form design:

[als_keyword label="Location (optional)" placeholder="e.g. County, Postcode or Town"]
[als_field name="make" ]
[als_field name="model"]
[als_field name="min_price"][als_field name="max_price"]

[als_button label="Search"]

The following image shows the behavior. Instead of clearing, the field is grayed out:

It is possible to have the field cleared instead of grayed out?

Thank you in advance