property popped

This property returns if the pop-up box is currently in a popped (open) state. This is mainly used for poppup boxes.

function ChangeDataIfPopped()
{
    var bx = scene.getBoxById("sampleMenuCtx");
    if (bx && bx.popped)
    {
        var otherBx = scene.getBoxById("backBox");
        if (otherBx)
            otherBx.setAttribute("myDataKey", "myDataValue");
    }
}