This feature is non-standard and is not on a standards track. Do not use it on production sites facing the Web: it will not work for every user. There may also be large incompatibilities between implementations and the behavior may change in the future.
The original target of the event before any retargetings. (Mozilla-specific)
originalTarget may also be native anonymous content (see bug 208427), in which case it's useless for non-privileged code.
See also Comparison of Event Targets
Need an example that makes sense here
This is a Mozilla-specific property. Defined in
This event property is not defined in the W3.org DOM Level 2 Events