I noticed a problem with VerticalFlexLayout in IE11 (and presumably older IE browsers).
The JS output causing problems has child.dispatchEvent(new Event("layoutNeeded")); The reason is that the org.apache.flex.events.Event import is missing from the COMPILE::JS build scope So it is falling back to what I assume is the native html Event class (via externs) This works fine in Chrome, but not so in IE11. Changing the actionscript source for VerticalFlexLayout to add import org.apache.flex.events.Event; to cover javascript as welll as SWF, fixes the issue. I then unzipped all the JS swcs and file-searched in the js output for 'new Event' It looks like there are a total of 14 cases of output in the js which are new Event('something') instead of new org.apache.flex.events.Event('something') These are in org.apache.flex.core.ApplicationBase (x6) org.apache.flex.svg.GraphicContainer (x3) org.apache.flex.html.beads.layouts.VerticalFlexLayout (x1) org.apache.flex.html.beads.layouts.HorizontalFlexLayout (x1) org.apache.flex.textLayout.edit.Clipboard (x3) I suspect these are import omissions that may cause bugs (perhaps only in certain older browsers). But thought I would check before doing any changes in case I am missing something that I don't understand about the events in js.... What do others think?