Hide dates columns on application startup

I created a new project using GanttProject 3.2 and I hid the two date columns (“Begin date” and “End date” columns).
Xml code:

<view zooming-state="default:2" id="gantt-chart">
        <field id="tpd3" name="Name" width="100" order="0"/>
        <field id="tpd12" name="Cost" width="100" order="1"/>
        <field id="tpd8" name="Coordinator" width="100" order="2"/>

Closing the project and reopening it, the application shows also startDate and End Date. Is it possible to keep them hidden?

Is there a place where I can find the possible values that I can assign to the taskproperties so I can modify directly the xml file?

Thank you in advance

It seems to be a bug. I created a new ticket:

thank you for your prompt response.