over.py

if mouse.events[events.LEFTMOUSE] == 1:
    hit = P.mOver.hitObject
    if hit is not None:
        mesh = hit.meshes[0]
        for v in range(mesh.getVertexArrayLength()):
            vert = mesh.getVertex(0, v)
            uv = vert.getUV()
            uv[0] += 0.5
            vert.setUV(uv)