What are you actually trying to achieve?
If it is “some raster maps in a webview in a desktop application” then I’d suggest just using something like Leaflet - if your webview can run Javascript, it should work.
Embedding an entire site (osm.org) in an application’s webview isn’t guaranteed to work, since the site design makes assumptions about where it’s deployed.
If you “just want map editing”, have a look at things like MapRoulette.