[Feature Request] StageWebView/HTMLLoader "click through" transparent region support

[itlancer]

Feature Description

"click through" transparent region of StageWebView or HTMLLoader could be valuable to create applications with combination of DisplayList or Stage3D with HTML content displayed over it.
It supported by Electron and NW.js for example.

Right now there is no way to interact by mouse/touch with Stage below StageWebView or HTMLLoader (even with HTMLLoader::paintsDefaultBackground=false) (StageWebView doesn't support transparent background at all right now).

Sometimes it is important to display HTML content over AS3/AIR application and interact with UI below some transparent regions of such web pages.
There is no need to implement this feature for HTMLLoader if StageWebView in future provide AS3<->JS communication, navigation, more events, more control, DOM access, support for using with DisplayList and so on.

Related issues (not the same):
#143
#128

Known Workarounds

Write your own native extension with "WebView" (browser) implementation.