Without an export option in Passkeeper, i found a simple workaround to retrieve and save all passwords stored for your Maxthon account.
A minimum HTML knowledge is necessary to understand displayed information, and instructions to offline processing of retrieved information is not provided.
Be very careful, since saving passwords on a plain file is not safe!!!
From http://www.maxthon.com website, click on "My U+" menu on top, or directly go to https://www.uu.me
Login with your Maxthon account.
You should be now in your "Maxthon U+" web page: click on "Passkeeper" on top menu (password will be asked again).
You will now see a web page with the list of all your accounts and passwords (don't worry if they look "masked" by dots). This is NOT the Passkeeper tool embedded in Maxthon browser, but an ordinary/plain/unprotected web page with the same data.
With your browser, now right-click anywhere in the page and select "View page source" or anything similar, depending on the browser (this can be copied/pasted in a text editor or saved as plain HTML file for your own purposes, including offline processing in a more readable way, e.g. in an Excel file).
The HTML code is then shown, and there you can search for a line with this tag:
<table class="table table-mmds table-sort table-sort-search table-sort-show-search-count">
This is the beginning of the entire list of your accounts & password: for each list entry, you can easily see 4 "blocks of code":
a. the <td> tag for the table cell with the name of the site and the link to show details ('<a href="fav.html?m=see&unid=...')
b. the <td> tag for the table cell containing the Account name for the site ('<td class="caname search-item">...')
c. the <td> tag for the table cell containing the password for the account ('<td class="pwd-item capassword"><input type="password" class="originpwd" name="password" readonly value="PASSWORD">...') [yes!!! That is your password for the site, fully readable!!!]
d. the <td> tag for the table cell with the web address of the site ('<td class="orgin-item search-item caurl"><span>...')
Check it out!!!
Just concerned about Maxthon security, if an unprotected web page can be generated and saved in such an easy way...