Comment 9 for bug 1473471

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Albert Astals Cid (aacid) wrote :

So after three days of debugging I've been able to figure out why it is crashing, why it's random and i can provide a quick workaround in unity8 code.

## Why is it crashing? ##

The problem exists because we use the QML cache and because Qt has this bug https://bugreports.qt.io/browse/QTBUG-47709

The bug in Qt means that if for types with extended properties (Image and "source" in our case coming from the SDK) an Item is created before the type is extended, all subsquent items of the same type won't see the extended property either.

Since we're using the QML cache this means that the code loaded from the cache expects the extended property to be there, so when it access such property, it will crash.

## Why is it random? ##

It's random because the QML file loading is not always done in the *exact* same order, and thus in some cases the first Image is created in a file that imports Ubuntu.Components and in some cases the first image is created in a file that does not.

## How to workaround it? ##

A quick workaround is making sure Ubuntu.Components is imported in the first file that is imported, in unity8's case UnityInputInfo.qml that is a singleton imported from the root file (OrientedShell.qml)