Top panel shifts down when hidden?

[littelbro14]

I know, minor problem. But on an otherwise clean and fresh looking desktop, that small shift down tends to throw off my chi. Also, it does tend to get in the way a bit, such as obscuring my options button in Chrome, rather than just taking up a bit of unused space on my tabs bar. Wasn't having this issue with 10.04, but started happening immediately after upgrade.
Example of what I'm talking about:
Unhidden
http://imgur.com/rkgxJ.png
Hidden
http://imgur.com/nGC62.png

[Tamlynmac]

One thought is, it appears you may have "show hide buttons" turned on in your panel properties? The button appears in both your screen shots. I've find the button unnecessary and turn it off. By simply moving my mouse to the top of the screen (in auto hide) the panel becomes viewable. The delay time is adjustable in the configuration editor.
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right click on panel and select properties. On the general tab is there a check mark in front of "show hide buttons.
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Just another quick thought, if you need to keep the button. Have you checked the auto_hide_size in the gnome configuration editor?
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menu/system/configuration editor/apps/panel/top_panel_screen/auto_hide/size
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This particular key determines the visible number of pixels when the panel is hidden in a corner. It will take a value lower than zero, which may move it off the screen. Even it it drops down at least you may be able to make it small enough that it becomes a non-issue or even move it off the screen.

Good Luck and hope this helps