Qt 5.7.1 as shipped by KDE neon User LTS has some bugs that should be fixed in newer versions, particularly Qt 5.9+. It would be nice if KDE neon could update to such version in order to fix these bugs. See-Also: https://bugs.kde.org/show_bug.cgi?id=378283 See-Also: https://bugs.kde.org/show_bug.cgi?id=383413
Current Plasma LTS is not compatible with Qt 5.9 and actively advised against combining by at least the KWin maintainer.
Are fixes for Qt bugs (e.g. for bug #378283) being backported to 5.7.1? In that case I would re-purpose this request accordingly.