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QT webengine webenginewidgets
How to add webengine webenginewidgets into Qtrpi on ubuntu ?
By instinct I would say
apt-get install libqt5webengine5 libqt5webenginewidgets5and likely
apt-get install qtwebengine5-dev. However you should give more details.
Are you cross-compiling ?
Are you developing directly on the Pi ?
I am cross compiling
This display is coming
Did you cross-compile QtWebEngine first ?