Opera has a strange behavior dealing with iframes.

Opera doesn't fire the onload event of a page contained in an iframe if there is at least another iframe that is downloading something.

This bug does not casue any issue to Lightstreamer. But if you have your own iframes in a page that contains the lsengine.html file inside an iframe (even if created by Lightstreamer Web Client) you might not receive the onload event on yours.

There are several approaches to work-around the problem:
-You can start the LightstreamerEngine in DISCONNETED mode and then turn it to STREAMING once you have received all the desired onload calls
-You can start the LightstreamerEngine in POLLING mode, this way between each polling request the browser may have the time to call the onload events on other pages and then you can turn LightstreamerEngine to STREAMING
-You can avoid to depend from the onload event and use a different strategy instead

A test-case can be found here (click TEST to start)
There is also an entry with a similar problem on Opera's forums: http://dev.opera.com/forums/topic/168147