Necessity of declaring library versions

Matthew0x

Hello,

I am using the newest 6.1.3 version of Qt and I mostly play around QtQuick with pre-configured animation types (like already declared window/tabs classes etc.)

I spent some time in the previous version of Qt (5.8?) and made myself a small application with some transparency in windows, custom SVG and like that. The point is, I believe that back then the headers like

import QtQuick 2.9

had the version explicitly specified.

As of 6.1.3 I ran the application with just the "import QtQuick" (or similar) directives
(it's the default behavior, I didn't change it until just now).
It did compile, producing a working window with tabs and everything inside (labels for now).

Summing up. I am trying to bring more content into my tabs and I want to create user input etc.
I noticed that

this specific view panel (Form Editor) would have trouble rendering the objects inside the Page object.
The point is, the compiler returns me warnings (not visible in compile output though), when the version isn't specified.

The tab then doesn't render properly

However, the program does compile

I can provide library versions and be able to continue, however the question is.
Where do you find the lists of newest/compatible libraries?

The editor does hint at some versions (in the form of available numbers), however it's not always reliable.
When using the

import Qt.labs.platform

the text editor suggests version 1.0, which can't be compiled with the SystemTrayIcon object.
I believe that the compiler can find the newest/compatible library and render/compile the objects, but the editor doesn't know where to find them?

I must use this specific declaration without version number, or else I get the error:

QQmlApplicationEngine failed to load component
qrc:/main.qml:16:9: "SystemTrayIcon.icon" is not available in Qt.labs.platform 1.0.

Is this the expected behavior, am I doing something wrong?
Where could I find the list of available libraries and their versions?

I tried looking up the Qt 6 documentation, but it doesn't seem to provide those numbers.