DOM element in a plot doesn't get mouse events

[msdvoits]

Open samples/DOM elements in a plot.html.

Observed:
When I hover the mouse pointer over the label "Start of the curve" it doesn't become bold.

Expected:
It must become bold because there is an appropriate CSS style in the HTML file:

    <style>
        .idd-dom-marker:hover
        {
            font-weight:bold;
        }
    </style>

It seems that the same problem is with NestedChartAsDomPlot.html: the nested chart doesn't reacts on navigation gestures but propagates them through to the outer plot.