Currently there are 7 native Wideangle Zoom lenses for Panasonic GH3 and all of these lenses are autofocus (AF) type.
Panasonic GH3 doesn't have a sensor based image stabilization system and none of these lenses have optical Image Stabilization.
Since Panasonic GH3 has environmental sealings (Weather Sealing), you may like to couple your camera with one of these 4 Wideangle Zoom lenses with Weather Sealings.