That's great!
Thank you for posting back to let me know.

First of all, please ensure that you are viewing your web site over a wi-fi connection and not 3G/4G.
If using 3G/4G, then please see this FAQ which offers a solution.
Why can't I view my gallery on a 3G mobile connection?

Also, your gallery uses the Juicebox-Pro v1.4.2 JavaScript file but the Juicebox v1.2.0 CSS file.
Try replacing your gallery's current 'jbcore' folder with a fresh version from your Juicebox-Pro download zip file ('juicebox_pro_1.4.2/web/jbcore/') to ensure that all files are from the same version of Juicebox-Pro.

Within a gallery, Juicebox reserves space for the thumbnails and the remainder is used for the image area. This is true no matter what the dimensions of the gallery are.
By default, Juicebox then scales the main image to fit within the image area as large as possible without cropping but whilst respecting the image's aspect ratio.

In your test gallery, image #4 is a different shape to image #3.

If the image has a different aspect ratio to the image area, then the only way for Juicebox to fill the image area with the image would be to set imageScaleMode="FILL" (although, for image #4 in your gallery, this would result in the left and right edges of the image being cropped).

Another possible solution to reduce the space above and below image #4 in your gallery would be to reduce the gallery's height so that the aspect ratio of the image area within the gallery matches the aspect ratio of your images.

Please see this FAQ for further information.
My Juicebox gallery shows too much space above or below the main image, how do I fix this?

The most likely way to have a third-party editor installed would be through the use of a plugin (or, less likely, through a theme).
It seems unlikely that WP-Juicebox would detect CKEditor or FCKeditor unless such an editor was being used. If you have tried any third-party editors in the past, then perhaps they have not been fully deactivated and uninstalled, resulting in some files begin left behind that WP-Juicebox is detecting.

If you have already checked your plugins and would like me to investigate further, then I would be happy to do so but I would need access to your WordPress installation and web server. If you are agreeable to this, then please let me know and I will send you an email address where you can forward your WordPress and FTP login details on to me. Thank you.

The sort argument within the Flickr API (which is what Juicebox uses to fetch the images from Flickr's servers) supports only the values I mentioned above (and listed on the Flickr API support page).
One way to order Flickr images alphabetically would be to display a Flickr Set (via the Juicebox-Pro flickrSetId configuration option) and to order the images within the set alphabetically within Flickr itself (following the instructions here).

This error message should be displayed only if a variant of CKEditor or FCKeditor is detected (and WYSIWYG mode is not selected). (It should not be displayed when using the defautl TinyMCE editor.)
Please check that you do not have any plugins installed and activated which use CKEditor or FCKeditor.

@kilooloogung

Just in case you are not aware, Juicebox-Pro has built-in support for a Back Button (without the need for any manual coding) which can be either text or an icon.
Please see here for the available Back Button configuration options.

@wspollack

That's right. It is much easier to overlay an HTML element on top of a gallery (which will always be in exactly the same place on the web page), as kilooloogung has done, than to try to introduce a new custom button within the gallery's own Button Bar (which would be fraught with problems, especially without access to the Juicebox source code).

What you are describing actually sounds like the Splash Page (which is displayed by default on small screen devices).
For more information on Screen Modes and the Splash Page, please see here.

First of all, I would recommend using a fixed pixed height for your gallery. If you use a percentage height as you currently do (80%), you need to ensure that the parent container(s) of the gallery have heights specified via CSS, otherwise Juicebox may not be able to calculate its own height (it needs to know what its height should be 80% of). This can be difficult to control in a WordPress environment where the gallery's parent containers are generated by the theme. (This is why the default height for a gallery created by WP-Juicebox is 600px.) Please see this note regarding Using Percentage Heights.

Try setting showSplashPage="NEVER" in your gallery's Pro Options text area to embed the gallery directly into the page in Small Screen Mode instead of the Splash Page.
Alternatively, try setting screenMode="LARGE" to force the gallery to be displayed in Large Screen Mode in all browsers and on all devices. (By default, Large Screen Mode does not use the Splash Page. The Splash Page will be used in Large Screen Mode only if showSplashPage="ALWAYS".)

Also, after making any changes, please be sure to clear your browser's cache before reloading your gallery's web page to ensure that your browser is fetching and using the most recent versions of your gallery files from your web server.

@RajabNatash

I notice that you have copied your posts from your Drupal forum thread to this thread. Thank you for posting your findings in this forum.

The bug reported by the original poster (whereby scrolling down a page with an embedded gallery jumps to the top) has been addressed and will be fixed in the next version of Juicebox (although I do not know when it will be released).
If you would like to be notified when new versions are released, then please join the mailing list at the foot of our homepage, follow us on Twitter @JuiceboxGallery or subscribe to our blog RSS feed.

The developers are also aware that 'minimal-ui' has been removed from iOS 8 and this will be taken into account in the next version of Juicebox.

No problem.
I'm glad it was an easy fix!

Use the following code for the gallery to be displayed in the live preview window. The 'directory' value will be written to the gallery's 'config.xml' file only when the gallery is exported (and not in preview mode).

local dir = ""

for index, value in ipairs(pro_options) do
    if value ~= "" then
        local attrs = explode("=", trim(value), 2)
        if table_length(attrs) == 2 then
            local key = escape(attrs[1]:gsub("%s+", ""))
            local value = escape(trim(attrs[2]):gsub("^([`'\"])(.-)%1$", "%2"))
            if key:lower() == "directory" then
                if mode ~= "preview" then
                    dir = value:gsub("/*$", "") .. "/"
                end
            elseif not lite_options[key:lower()] then
                write("\n" .. key .. "=\"" .. value .. "\"")
            end
        end
    end
end %>
>

<% for index = 1, numImages do %>
    <image imageURL="<%= dir %>images/<%= getImage(index).exportFilename %>.jpg" thumbURL="thumbs/<%= getImage(index).exportFilename %>.jpg" linkURL="<%= getImage(index).metadata.linkURL %>" linkTarget="_blank">
        <title><![CDATA[<%= strip_control_characters(getImage(index).metadata.title) %>]]></title>
        <caption><![CDATA[<%= strip_control_characters(getImage(index).metadata.caption) %>]]></caption>
    </image>
<% end %>

</juiceboxgallery>

You might like to know that we are currently working on a new Lightroom plugin which will feature all Pro configuration options in the interface (removing the need to type them into the 'Pro Options' text area).

Thank you for clarifying.
As I'm sure you are aware, the Juicebox fullscreen gallery was designed to completely fill the browser window (or the entire screen if useFullscreenExpand="TRUE"). It was not designed with user modification in mind (for example to reduce its size).
Perhaps the following notes will be of interest.

Your original problem (with overlapping elements) may stem from a known bug whereby elements which have explicitly been assigned a CSS 'position' are not covered by the fullscreen gallery (they should be). This bug has already been addressed and will be fixed in the next version of Juicebox.
In the meantime, a workaround would be to set expandInNewPage="TRUE" so that, when the gallery is expanded, it will be displayed on a page of its own rather than on top of the embedding page.
With the expanded gallery no longer showing any elements from the embedding page, visitors to your web site could then use the Expand/Close Button within the gallery to close the expanded view (to return to the original embedding page) and you could also use the Back Button functionality to add a link within your gallery to whatever web page you like.
I hope this helps.