title: Change line thickness for specific line in ggplot in R
body: <p>I would like to change the line thickness for <code>State = "A"</code> to 2, but <code>scale_size_manual</code> doesn't seem to work for <code>stat_smooth</code> type of line-plotting.</p>
  
  <p>Could someone let me know how to change line thickness for this specific condition?</p>
  
  <pre><code>   aaa = data.frame(State=rep(c("A","B","C"),100),x= rnorm(300),y=rnorm(300))
     ggplot(aaa,aes(x=x, y=y,col=State))+ 
            geom_point() + 
            stat_smooth(method=glm,se=FALSE,aes(col=State)) +  
            scale_size_manual(values = c(2,1,1))
  </code></pre>