Repro:

• Open wldf.jfr
• Go to Java Application
• Select thread ..ExecuteThread '4'
• Open the lane editor and add the EJB Business Method Invoke event to the Servlet Request Run lane, disable the EJB Business Method Invoke lane
• Zoom into time around 12:08:30
• There is now a EBMI event (purple) that is completely covered by the SRR event (red), and is not visible in the tooltip (Selecting the time range of the SRR event makes the full event set be displayed in the Properties view)
• Zoom in further and the EBMI event appears in the chart and in the tooltip

This is sort of by design, but could be considered to be changed, might be costly to calculate?

The desirable behavior (requested for example by stefank) would be to draw the shorter events on top of the longer ones.

Workaround in stefank case is to view his special Z GC events on a customized page, and group first by thread and then by event type (or in his case the Name attribute), and the events will appear in different lanes, but it's not a general solution.