if(
(!win || win->getVisibilityMode() == Window::VM_PARTIAL) &&
!win->isPointerXYWithinVisible(x, y)
) continue;
But it probably should be
if (!win || (win->getVisibilityMode() == Window::VM_PARTIAL) && !win->isPointerXYWithinVisible(x, y)))
continue;
The effect of the bug is to segfault if a non-osgWidgets::Window node hasn't been excluded from picking via NodeMask."