The main bar included by using the taglib <@cms.mainBar...> does not append the URL parameters supplied to the webpage.

Example:

We have a web page with URL: /my-site/partners.html which takes the optional parameter "name" (/my-site/partners.html?name=Partner1).
The <@cms.mainBar...> results in this:

<select name="locale" id="locale" onchange="window.location = this.value">
<option value="/my-site/en_US/partners.html" selected="selected">English (United States)</option>
<option value="/my-site/partners.html">Svenska (Sweden)</option>
</select>

When it should be like this:

<select name="locale" id="locale" onchange="window.location = this.value">
<option value="/my-site/en_US/partners.html?name=Partner1" selected="selected">English (United States)</option>
<option value="/my-site/partners.html?name=Partner1">Svenska (Sweden)</option>
</select>