LV::Video.fill_color(Color const &color, Rect const &area) does not work

[davidwe]

video->fill_color ( LV::Color(0,120,0), video->get_width(), video->get_height() );
video->fill_color ( LV::Color(0,120,0), LV::Rect area(10, 10, 20, 20) );

Both commands result in a entire black screen, while the rectangleless version of the method gives a nice dark green.

[kaixiong]

Depends on #64.