[KevinH]

FWIW, the implementation in the KDE plugin for QFileIcon provider uses fromTheme as well:

	QIcon KdePlatformTheme::fileIcon(const QFileInfo &fileInfo, QPlatformTheme::IconOptions iconOptions) const
114		{
115		    if (iconOptions.testFlag(DontUseCustomDirectoryIcons) && fileInfo.isDir()) {
116		        return QIcon::fromTheme(QLatin1String("inode-directory"));
117		    }
118		
119		    return QIcon::fromTheme(KIO::iconNameForUrl(QUrl::fromLocalFile(fileInfo.absoluteFilePath())));
120		}

And the simple testcase does the following:

QListWidgetItem *firstItem = new QListWidgetItem(QIcon::fromTheme("dialog-information"),
                                                     "ONE");

So my guess is that QIcon routine is or its themed version is where the trouble may be.