Make it look like Safari 3?
P
Pro... Right up front I can say that my old G4 iBook runs Safari 4 on Tiger, a lot faster, with fewer hangs caused by slow javascript files. Bravo for this big improvement.
Con... I don't like the placement of the new tabs bar across the very top of the browser window. No sir... I don't like it at all. It makes me feel as if there are a bunch of open windows sticking up behind the window at the front. Now I'm sure that this is a very logical layout since each tab is (in reality) another open browser window waiting for its' turn to be on top of the stack. Problem is... I usually have several browser windows with tabs open on each of them, and several program windows (dreamweaver, fireworks, etc) opened on my desktop, too. I juggle these open windows on my 3x4 proportioned laptop screen by pulling a window's edge off to one side, and another a bit lower, and one a bit higher so I can click on each window's edge as my workflow demands. The multiple tabs across the top of the new Safari browser screen just makes my desktop feel more cluttered. Sure, there are work around solutions for my particular style of working, but I prefer the older style of placing the tabs below the tool bar because that is what I am used to. Obviously it comes down to personal preference.
When apple releases osx 10.6 later this year, I will get a new machine and see if this tab positioning works better for me, on a wide screen mac.

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