In my case, WebKitGTK 2.40.x works correctly without any issue. It is only with WebKitGTK 2.41.x that I get a blank screen. I can corroborate that web pages seem to be rendered but not shown, and dragging items of the page generate a thumbnail that follows my cursor as expected. Moreover, disabling DMABUF causes the web view to show the correctly rendered page, but the tab hangs quickly after.
In my case, WebKitGTK 2.40.x works correctly without any issue. It is only with WebKitGTK 2.41.x that I get a blank screen. I can corroborate that web pages seem to be rendered but not shown, and dragging items of the page generate a thumbnail that follows my cursor as expected. Moreover, disabling DMABUF causes the web view to show the correctly rendered page, but the tab hangs quickly after.