addButton({
    display: ({ selection }) => selection.hasSelection() ?
      { type: "unlink"  } :
      "",
    onClick: async ({ selection }) => {
      const text = selection.getSelectedText();
      const unlinked = text.split("\n")
        .map(line => line.replace(
          /\[((?:[^\[$!"#%&'()\*\+,\-\.\/\{\|\}<>_~]\s?|[\[$!"#%&'()\*\+,\-\.\/\{\|\}<>_~]\S)[^\[\]]*)\]/g,
          "$1"
        ))
        .join("\n");
      if (text === unlinked) return;
      await insertText(unlinked);
    },
  });
  addButton({
    display: ({ selection }) => selection.hasSelection() ?
      { type: "strikethrough"  } :
      "",
    onClick: async ({ selection }) => {
      const text = selection.getSelectedText();
      const striked = strike(text);
      if (text === striked) return;
      await insertText(striked);
    },
  });
  addButton({
    display: ({ selection }) => selection.hasSingleLineSelection() ?
      { type: "code"  } :
      "",
    onClick: async ({ selection }) => {
      const text = selection.getSelectedText();
      await insertText(`\`${text}\``);
    },
  });
  addButton({
    display: ({ selection }) => hasURL(selection.getSelectedText()) ? "URL" : "",
    onClick: async ({ selection }) => {
      const text = selection.getSelectedText();
      const converted = await convertURL(text);
      if (text === converted) return;
      await insertText(converted);
    },
  });
  addButton({
    display: ({ selection }) => getLink(selection.getSelectedText()) ? "update a link" : "",
    onClick: async ({ selection }) => {
      const text = selection.getSelectedText();
      await replace(
        text,
        [scrapbox.Project.name, "takker", "takker-memex", "takker-private"],
      );
    },
  });