What is the best way to hide a field visually?

[Guido1982]

OK, I've done some tests, but without success:

Code:

<map>
    <originmodule>
        <originname>SalesOrder</originname>
    </originmodule>
    <dependencies>
        <dependency>
            <field>subject</field>
            <condition>
            [
                {
                    "groupid":"",
                    "columnname":"vtiger_salesorder:subject:subject:SalesOrder_Subject:V~M",
                    "comparator":"e",
                    "value":"",
                    "columncondition":"or"
                },
                {
                    "groupid":"",
                    "columnname":"vtiger_salesorder:subject:subject:SalesOrder_Subject:V~M",
                    "comparator":"n",
                    "value":"",
                    "columncondition":""
                }
            ]
            </condition>
            <actions>
                <hide>
                    <field>pl_gross_total</field>
                </hide>
            </actions>
        </dependency>
    </dependencies>
</map>

I've also tried emptying the 'condition' and completely removing it, but the 'pl_gross_total' field is still there.