After going live with Dev6i patchset 19, we faced issues in many forms where the flexfield would not pop up if mouse was clicked. Tab worked fine, but mouse click didn't work.
As per metalink note 753704.1 and 753702.1, it’s a known issue and we need to apply forms patch 7482264 and force regenerate jar files to fix it. We were able to reproduced the issue in a test instance. We applied the patch to the test instance and it resolved the issue.
We are now doing regression testing to ensure that this one off patch has not created new problems as indicated in some other bugs.