"QUICK SEARCH" at the top right of each page is very useful, but when working on a project you probably want to "quick search" an issue only on the project you are currently working on...

for installation of jira with an high number of configured projects (try https://issues.apache.org) quick search is pretty useless without filtering on a specific project, and "smart search" which filters on a project key is a too hidden feature to work for the majority of users.

What about adding a checkbox (or anything similar), on by default, near to the "quick search box" in order to limit the search to the "current" project (if one is selected, just like when you click on "browse projects")? This could be a great usability improvement for most users...