HalftonePreviewView
class HalftonePreviewView : public BView
HalftonePreviewView(BRect frame, const char* name,
HalftonePreviewView* fPreview;
HalftonePreviewView::Preview(float gamma, float min,
fPreview = new HalftonePreviewView(r, "preview", resizeMask, flags);
HalftonePreviewView::HalftonePreviewView(BRect frame, const char* name,