Change EventMarker Label style

Hello.

markerLabelStyle does not seem to work at all for when the type of the EventMarker is "flag". (it works ok when it's a point)

What I am trying to do is change the color of the label, but it stays grey.

My code:

```
> not working
stemStyle={{ stroke:"black" }}
markerStyle={{ fill: "black" }}
infoStyle={{ fill: "white", stroke:"black" }}
/>
```