Comment 2 for bug 1103768

Specifically on lines 591-594 in plugin.vala:
    float scale_x = (float)ew / width;
    float scale_y = (float)eh / height;
    float anchor_x = (float)(x - ex) * width / (ew - width);
    float anchor_y = (float)(y - ey) * height / (eh - height);