QFile:copy does not work properly for resources on Windows

When the sourceFile is loaded from the resource, like "QFile::copy(":/mydata.txt", "C:\mydata.txt");"

Then the targetFile can not be deleted programatically.

Calling QFile::remove(C:\mydata.txt");

will fail. But the file exist and can be deleted in Explorer.
This only happen when the file is copied from from the resources.