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Modify the file /atlassian-jira/secure/admin/user/views/userbrowser.jsp to get a UI 'SU' link. Find the following (starting around line 182 in JIRA 5.2), the bold section is added to make the SU link visible.
<td data-cell-type="operations">
<ul class="operations-list">
..<li><a id="su_link_<webwork:property value='name'/>" href="<ww:url page='JiraSU.jspa'><ww:param name="'name'" value='name' /></ww:url>">SU</A></li>
<li><a id="projectroles_link_<ww:property value="name"/>" href="<ww:url page="ViewUserProjectRoles!default.jspa"><ww:param name="'name'" value="name" /><ww:param name="'returnUrl'" value="'UserBrowser.jspa'" /></ww:url>"><ww:text name="'common.words.project.roles'"/></a></li>
...
</ul>
</td>
Pre-modified files:
For the time challenged, assuming no other customizations, copy the appropriate file to /atlassian-jira/secure/admin/user/views/userbrowser.jsp
The manual approach
Jira 3.x - 4.1.x Add the following beneath it:
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