Changing visibility of subform on masterpage(s) - reverted after event

[ulibaehr]

In a click event change the visibility of a subform on a masterpage.

Code looks like this:

const sMasterpage = "openimmo.#pageSet.Seite1";

    // find all incarnations of this master-page type:

    var arrayMasterpages = xfa.resolveNodes(sMasterpage + "[*]");

    for (var i = 0; i < arrayMasterpages.length; i += 1) {

	arrayMasterpages.item(i).resolveNode("gruen").presence = "visible";
	} // for i xfa.host.messageBox("test");

The strange thing is: Up to the messageBox the subform is visible. But as soon as the click event ends the subform is hidden again.

I find that hard to understand.

Has anyone ever had this effect?