I know that that’s the way it’s supposed to behave. I only happen to think it’s ill thought (and I’m not the only one).

For one, it destroys the identifiability of your Stacks. The ever changing top-most icon makes identifying the download stack among your other dock icons difficult, and makes different stacks difficult or impossible to tell apart (without opening them or hovering to read their title). Good luck trying to differentiate between the Downloads and Documents stack.

Furthermore, superimposing the icons from several different downloaded files behind the latest one, looks butt ugly.

The “overlay icon” solution keeps the “latest downloaded file is on top” behavior (which you like), but also helps you visually differentiate between different stacks by looking at the lower half of the icon (the overlay).

The ideal solution would be for Apple to incorporate something like this (perhaps a badge?) to Stacks. Then we wouldn’t have to resort to hacks like these, adding a useless folder in our stacks and sorting them by modified date just to get a top-most icon overlay.

“The problem was that it shows as a Dock icon the icon of the latest downloaded file with the rest of the downloaded file icons behind it. Meaning that the frontmost icon changes all the time: now it’s a document icon., not it’s an application icon, now it looks like a zip archive. What was Apple thinking?”

That’s exactly how it’s supposed to behave - that way you can see what you downloaded last - The stacks are by far my favorite organizational tool in Leopard and have made files on the desktop a thing of the past…

We’re using special stacks on all the public iMacs at my University to give users all kinds of great features without having them dig through any folders.

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then restart the dock, empty your trash, and restart your dock again.

Side panels like in the Finder and Mail? Well, it depends on the application. Generally you can adjust their size (up to a point) by dragging them.

On Mail you can select View -> Hide Mailboxes to close the sidebar.

On Finder (and most other applications) you can click on the pill shaped button on the top right to trim the window, by loosing the sidebar, toolbar and other superfluous stuff.

I’m not aware of any other way to turn Finder’s sidebar off.