QtWidgets based examples are rendered at half viewport size with latest QtBase 5.6

When compiling latest QtWebEngine 5.6 with latest QtBase 5.6, and running demobrowser example, the widgets are rendered at half the window size, but the web page is rendered normally within the half window viewport.

QML based quicknanobrowser works fine.

Note that when you hover the mouse where content should actually be, it changes the cursor, so coordinates computing seem to work ok.

See attached screenshot.