[Dillo-dev] [un]highlighting and drawing lines

Yesterday, I noticed that simply clicking on a random spot on a page caused a bunch of drawLine()s. This turned out to be an unnecessary unhighlight. The attached code is what I got from playing around to see how much highlighting and unhighlighting is unnecessary. (Highlighting part of a single word was still relatively inefficient, but there was a variable named brute_highllighting controlling it, so I figured it was for a good reason.) However, if I move the mouse around more rapidly, I get a lot fewer mouse motion notifications, which means to some degree that we're doing redraws when the motion is slow enough that we can more likely afford it. It might be different over a network; I don't know. Any opinions?