clicking "+ New filter": markers and marker borders swell when zoomed

[mrjones-plip]

Overview

when you have a map with markers for lat long cordinates and you zoom in and then click "+ New Filter" the markers swell, getting bigger and the stroke gets bigger too.

version 1

steps to reproduce

1. go to https://bl.ocks.org/melalj/cc130ad4072a2f52a5aa
2. zoom in on a maker as far as you can
3. click "+New Filter"

expected: markers and marker borders don't change size or stroke
actual: markers swell bigger and the stroke increases
work around: filter zoomed all the way out, then zoom in. or zoom back or zoom in (if avail) one level after filtering and zoom back in.

version 2

steps to reproduce

1. go to https://bl.ocks.org/melalj/cc130ad4072a2f52a5aa
2. click "+New Filter"
3. zoom in on a maker as far as you can
4. click "-Remove Filter"

expected: markers and marker borders don't change size or stroke
actual: markers swell bigger and the stroke increases
work around: filter zoomed all the way out, then zoom in. or zoom back or zoom in (if avail) one level after removing filter and zoom back in.

[melalj]

Fixed on #46