[bug] Tooltip closes when mouseover a X grid line

[pedrorfernandes]

In this example: https://naver.github.io/billboard.js/demo/#Grid.OptionalXGridLines

When hovering the mouse over one of the option X lines (label 1, 2, 3), we trigger a mouseout event
This causes the tooltip to disappear until the next mouse onover event

fromElement: <rect x="0" y="0" width="734" height="266" class="bb-event-rect"></rect>
toElement <line x1="655" x2="655" y1="0" y2="266" style=""></line>

The other optional Y grid lines + grid lines do not trigger this event
I'm not familiar enough with the html structure to suggest a fix, but shouldn't the event-rect ignore all elements below?

[netil]

HI @pedrorfernandes, thanks for the report.
For the workaround add below rule. I'll be fixing for the next release.

.bb-grid bb-grid-lines {
    pointer-events: none;
}

or use grid.lines.front option.

grid: {
    lines: {
        front: false
    },
}