beforeShow

fires before a Container control is shown

beforeShow: () => boolean | void;

Returns:

Return false to prevent a control from being shown; otherwise, true.

Example

form.getItem("container").events.on("beforeShow", function() {
    console.log("beforeShow");
    return true;
});

Change log:

• The event was added in v7.2
• The value parameter was removed in v8.0