Custom type reference fails with <customControl> is not a type. Why?

[Stokestack]

Hi all. New to Qt Quick and QML. Following a tutorial in a book, but it's failing and I don't know why.

I have two QML files...

MyToolbar.qml:

import QtQuick 2.12

Rectangle
{
	color: "gray"
	height: 50

	Rectangle
	{
		id: purpleRectangle
		width: 50; height: parent.height
		color: "purple"
		radius: 10
	}

	Text
	{
		anchors.left: purpleRectangle.right
		anchors.right: parent.right
		text: "hello there."
		font.pointSize: 30
	}
}

and then main.qml

import QtQuick 2.12
import QtQuick.Window 2.12
import QtQuick.Layouts 1.12

Window
{
	visible: true
	width: 640; height: 480

	Rectangle
	{
		width: 200; height: 200
		color: "red"
	}

	MyToolbar
	{
		id: myToolbar
		width: parent.width
	}

	RowLayout
	{
		anchors.top: myToolbar.bottom
		anchors.left: parent.left
		anchors.right: parent.right
		anchors.bottom: parent.bottom
	}
}

Both files are in the project file. This fails with

W libgallery-mobile.so: QQmlApplicationEngine failed to load component
W libgallery-mobile.so: qrc:/main.qml:16 MyToolbar is not a type

I don't see anything missing from what the book shows. Any ideas? Thanks!

Additional note: This looks a bit suspicious, with MyToolbar.qml not under Resources. But I don't know how this folder is populated:

[Nifiro]

[Stokestack]

@Nifiro Thanks for the reply. I had tried that at the Resources level, but got a blanket "Couldn't add..." error with no explanation. Also tried dragging, which doesn't work.

Any idea why Qt Creator lets you create QML files and then adds them to a "QML" folder but not to the resources?