Sometimes the longitude values of the bounding box are malformed (long < -180° || long > 180°).
Happens when zooming all the way out so that "many worlds" are visible and then panning to one of the "neighbouring worlds".

Possible fixes:

1. Leaflet/Leaflet#1885 (comment)
2. Don't allow to zoom out so much.

Something is wrong, if one tries to delete any but the last district. Problem most probably related to numbering of "item" classes and "WikidataIds" array.

Remove tooltips via CSS, when in small screen mode (Else black box on left side)

Currently only works for the first 2 districts. Related to node count.

• "Make request to overpass dependent on current zoom level of map." Not always a good solution (e.g. Seoul districts have admin_level 6. They only show up, when zoomed out too far).
  Instead: Beginning from a minimum zoom show everything.

• Activate checkmark (checked="checked") on newly added district
• If district with checked checkmark is deleted --> check the checkmark of first district

After each change save a version of "wikidataIds" in a new variable. For this it is best to change "wikidataIds" to an object similar to this:

var wikidataIds = {
//"key":  values (an object with a string and an array in this case)
    "0": 	{name:"District 1", ids: [1,2,3]},
    "1": 	{name:"District 2", ids: [4,5,6]}
};

//Access values
console.log(wikidataIds["0"].name); //Brackets needed because of number-only key name
console.log(wikidataIds["0"].ids[1]);
//Or like that
var x=0;
console.log(wikidataIds[x].name);

//Change value
wikidataIds["0"].name="Eastern District";
console.log(wikidataIds);

Make sure that all elements fill out screen completely in vertical direction on large screens. For this the navbar and details ("help") needs to be added to "#content" grid and change value "height: 100vh;". See this stackoverflow post

Just like on Wikidata Extractor. Some smooth scrolling would be nice to have (http://jsfiddle.net/hf4gap4v/, https://stackoverflow.com/questions/17631417/css-pure-css-scroll-animation)

• Add a textarea, where people can paste their GeoJSON from an overpass turbo query.
• Write help text. Take this older revision of Wikidata extractor as a template.

e.g. <input type="radio" name="selected" title="Activate district to add/remove polygons">

Example:
{{Mapshape|type=geoshape|wikidata=Q158089,Q4071168,Q158106|group=map1|fill={{StdColor|T1}}
|title=District 0}}

• Location: Top center
• Styling: Blue or green, slightly transparent

• On-the-fly download of OSM admin boundaries with help of overpass and maybe this plugin:
  Leaflet Overpass Layer.
  Try to have checkmarks on the map in order to show/hide certain "admin_levels".
• Alternative: Kartographer already uses a simplified polygon for each Wikidata ID. Maybe there is some way to tap this?

See this.

In order to select multiple districts in one go. Leaflet Lasso could be a good option.

Expected behaviour: Color of polygons should be removed & output window updated