Click-through window

[ultr]

If anyone needs the same effect on X11, here is the code:

#include <QX11Info>
#include <X11/Xlib.h>
#include <X11/extensions/shape.h>
 
MyWidget::MyWidget() : QWidget()
{
  QRegion region;
  XShapeCombineRegion( QX11Info::display(), winId(), ShapeInput, 0, 0, region.handle(), ShapeSet );
}

#include <QX11Info>
#include <X11/Xlib.h>
#include <X11/extensions/shape.h>

MyWidget::MyWidget() : QWidget()
{
  QRegion region;
  XShapeCombineRegion( QX11Info::display(), winId(), ShapeInput, 0, 0, region.handle(), ShapeSet );
}

To copy to clipboard, switch view to plain text mode 

You need link X11 extensions library. You may add this to your .pro file:
LIBS += -lXext

Note that window's decoration will still be clickable, so you will probably have to get rid of it.