Admin Panel - Media Problems

[kane-mason]

I am using the admin panel to upload media as it detailed in the uploading-files.md docs. My schema looks like this:

"media": {
  "additionalProperties": false,
  "properties": {
    "additional_pic_01": {
      "format": "file",
      "links": [
        {
          "rel": "Download File",
          "href": "/images/{{self}}",
          "download": true
        }
      ],
      "media": {
        "binaryEncoding": "base64"
      },
      "type": "string"
    },

In the admin panel the UI looks like this:

1. There is no way for me to clear the additional_pic_01 or any of the media properties, i can only select a new image. I can clear it via the json dropdown but this is cumbersome
2. Thumbnail - it states invalid data URI because i am using a custom storage implementation. What would be nice, if, similar to how you can specify the href for link, this could be used to specify a custom thumbnail URI
3. The general layout is not very pleasing. This is exasberated by the lack of a thumbnail, but in particular the Download File link seems like it belongs to the the picture below