when the user click on either the availability xmas tree lights or the events timeline ticker in the monitor>graphs pages, we need to display an overlay bar the vertically spans all graphs as well as displays the timestamp information for the time slice in question
rev2325 - prep work for displaying vertical overlay bar above the metric graphs;
rev2327 - finish the time line overlay; vertical span is from the bottom of the availability xmas tree lights to the top of the time line ticks for events; formatted time is display just under the time line ticks for events, centered below the overlay bar;
Tested overlay and event popups. Noted bugs and linked them here.
This bug was previously known as http://jira.rhq-project.org/browse/RHQ-1250 This bug is related to RHQ-1323