A solution to the lack of UI for Dash's user docsets in Zeal. Uses Python 3 and easygui (pip3 install easygui)

download_zeal_user_docsets.py

import os
import json
import tarfile
import urllib.request
import easygui
import configparser

user_docsets_url = 'https://dashes-to-dashes.herokuapp.com/docsets/contrib'
app_title = 'Download Zeal user docsets'


def get_user_docsets(url):
    response = urllib.request.urlopen(url)
    data = response.read()
    text = data.decode('utf-8')
    docsets = json.loads(text)
    return docsets


def choose_docset(user_docsets):
    msg = "Choose which user docset to download."
    choice = easygui.multchoicebox(
        msg, app_title, [d['name'] for d in user_docsets])
    return choice


def get_zeal_docsets_dir():
    config = configparser.ConfigParser()
    config.read([os.path.expanduser('~/.config/Zeal/Zeal.conf')])
    return config['docsets']['path']


def download_docset(url, directory):
    with urllib.request.urlopen(url) as response:
        with tarfile.open(fileobj=response, mode='r:gz') as tar:
            tar.extractall(directory)


def search_url(choice, user_docsets):
    return [d['archive'] for d in user_docsets if d['name'] == choice][0]


def confirm_docset_download(choice, docset_url, docsets_dir):
    return easygui.ccbox('The {0} docset will be downloaded from {1} and extracted into {2}.\n\nPlease wait.'.format(choice, docset_url, docsets_dir), app_title)


def docset_successfully_downloaded(choice):
    easygui.msgbox(
        '{0} docset successfully downloaded.'.format(choice), app_title)


def download_more_docsets():
    return easygui.ynbox('Do you want to download another docset?', app_title, ('Yes', 'No'))


def exit_message():
    easygui.msgbox(
        'Bye bye.\n\nPlease remember to restart Zeal to refresh the docsets.', app_title, 'Quit')


def show_exception(e):
    easygui.exceptionbox('Error: {0}'.format(e), app_title)

if __name__ == '__main__':
    try:
        user_docsets = get_user_docsets(user_docsets_url)
        while True:
            choice = choose_docset(user_docsets)
            if not choice:
                break
            for doc in choice:
                docset_url = search_url(doc, user_docsets)
                docsets_dir = get_zeal_docsets_dir()
                # if confirm_docset_download(doc, docset_url, docsets_dir):
                download_docset(docset_url, docsets_dir)
                #    docset_successfully_downloaded(doc)
            if not download_more_docsets():
                break
        exit_message()
    except Exception as e:
        show_exception(e)

Note - need to install tk, pip, easygui.

Edited original to fix Error: list index out of range
Edited original to loop through selections, downloading them all, instead of confirm on every selection.

Hi and thanks for this very useful script!
How about add a little sorting to make searching docsets easier?

get_user_docsets(url):
    response = urllib.request.urlopen(url)
    data = response.read()
    text = data.decode('utf-8')
    docsets = json.loads(text)
    return sorted(docsets, key=lambda x: x['name'])