We are hosting a WebView in an offscreen NSWindow and rendering to a CGContext as part of a NPAPI plugin. We proxy the events from the browser to the offscreen window and everything works well except for one thing: When I send a scrollWheel event through the normal event mechanism, I get inconsistent results. If the page itself is larger than fits in the view it seems that a NSScrollView is created and hosts it; this view scrolls with the proxied scrollWheel cocoa events just fine. However, when the page fits the bounds and there is a scrolling div inside the page these scrollWheel events are completely ignored. I have tried doing a hitTest and walking up the tree of superviews, even sending the event to each one, with no success. The source for the event dispatch code can be found here: https://github.com/firebreath/FireBreath/blob/master/src/libs/WebView/Mac/WebViewMac.mm#L408 This bug is consistent whether the npapi plugin is hosted in firefox, chrome, or safari. Facebook is looking to roll out a new Photo Upload plugin that will use this functionality on Mac but we are concerned about releasing something where the scroll wheel is completely inoperable. The WebView is used to provide a secure UI area where security-sensitive APIs can be used without any direct connection to the rest of the web page.
NPAPI support is removed from Safari 14 onward and it is not supported in Webkit Builds like WebkitGTK as well. I think this can be marked as "RESOLVED WONTFIX". Thanks! This bug was happening in NPAPI based plugin (can be valid by URL and Github page of source code mentioned in Comment 01).
Yup, won't fix.