Qt 5.15 released

As the last release of the Qt 5 series, we wanted to make sure that Qt 5.15 is a great release that you can easily upgrade to with your ongoing projects. It is, as always, fully backward-compatible with previous Qt 5 releases. A large amount of work has gone into bug fixes, and Qt 5.15 is the best and most stable release we've done in the Qt 5 series.

Qt 6 is expected before the end of the year.