Documentation
“Extend and customize search toolbar on the JIRA's issue search screen.”
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Features:
Highlight selected search bar fields
Clear search button
global search fields customisation
personal search fields customisation
Personal issue search fields customisation is available under configuration icon on the issue search bar. (YOUR_JIRA_URL/secure/ExtensiIssueSearchUserConfiguration.jspa)

Global search fields customisation is available for JIRA administrator in Administration → Add-ons → Issue Search (YOUR_JIRA_URL/secure/ExtensiIssueSearchGlobalConfiguration.jspa)
Configuration screen allows to customise main search fields located in the first row on the search bar and optional extended search fields located in the second row.
New clear button on the search bar allows to clear current search fields on the basic view or JQL query in advanced view.

