Transparency problems with system tray in Windows

[lliehu]

I use a class named SvgIconEngine that is subclassed from QIconEngineV2 to paint the system tray's (QSystemTrayIcon) icon.

SvgIconEngine *engine = new SvgIconEngine;
engine->loadSvgFromFile(":/icon.svg");
mSysTray->setIcon(QIcon(engine) ); // mSysTray = QSystemTrayIcon

SvgIconEngine *engine = new SvgIconEngine;
engine->loadSvgFromFile(":/icon.svg");
mSysTray->setIcon(QIcon(engine) ); // mSysTray = QSystemTrayIcon

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The paint code is the following:

void SvgIconEngine::paint(QPainter *painter, const QRect& rect,
    QIcon::Mode mode, QIcon::State state)
{
    mRenderer.render(painter, rect); // mRenderer = QSvgRenderer object
}

void SvgIconEngine::paint(QPainter *painter, const QRect& rect,
    QIcon::Mode mode, QIcon::State state)
{
    mRenderer.render(painter, rect); // mRenderer = QSvgRenderer object
}

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In Windows XP I have this problem:


Where there should be the transparency there are some weird colorful pixels which undoubtedly are not part of system tray's background.

I have this problem only in Windows. In Linux/KDE everything works perfectly.

Anyone has an idea?