Take screenshot of target (Framebuffer or QT)

Hello, does anyone know a quick way to take screenshots directly on the target (QT embedded / Framebuffer) ? I need it for the user-manual. Thank you.

Allready found something in google: QT provides QPixmap::grabWindow() for this purpose.

http://cplusadd.blogspot.com/2009/07/qt-embedded-capturing-screen-with.html

Any other ideas (maybe one without application-modification) ? Thank you.