[Development] Qt 6 co-installability with Qt 5

[Shawn Rutledge]

> On 2 Nov 2020, at 17:15, Thiago Macieira <thiago.macieira at intel.com> wrote:
> ]qml is like Python: because of plugins, it's tied to the Qt version. 
> Therefore, it fails the requirement for supporting everything the old version 
> supported. 

Well if you were using modules that are no longer supported, or you run into some little incompatibility; but we have been trying to avoid API breaks.  QML files that begin with “import QtQuick 2.0” still work fine so far; also Controls, Layouts etc.  So IMO it’s less onerous than the python upgrade.