Atlassian added a new issue-inline-editing feature with JIRA 5.1.

Zones is compatible with JIRAs inline-editing of Issues, although with some limitations for Zone Fields:

• If a user does not have Edit allowed permission on the Zone Field, inline editing is disabled for the user (See Configure Edit and Selectable Zones Permissions for Zones for details)
• If there are dependent Customfields for a Zone Field, the Zone Field will not be editable, because this would create inconsistencies.