Using the taskbar preview, we are able to switch tabs even when a modal dialog/window is open. STR: 1) Open two or more tabs 2) Tools -> Options 3) try and switch tabs -> can't due to the modal window being opened 4) Move mouse to taskbar, hover over Minefield icon to enable previews 5) Switch to a different tab even though we should be able to because a modal window is open IE8 respects the modal dialog and does not allow users to switch tabs

Sorry, step five in the STR should say "5) Switch to a different tab in the preview. We are able to switch tabs but we shouldn't be able to because a modal window is open.

Is this a browser modal window or a website modal dialog? If it's a website/javascript modal dialog, I think this is a feature rather than a bug. A website running in one tab should not be able to stop me from accessing information in other tabs. (One use case for this is looking up information in a second tab in order to know whether to press ok or cancel in the first.)

This is about both. But on the js-modal-dialog point: I think this is something, that needs to be done independently of this. If you develop in JavaScript it may happen that you you put some alert() in the code - for debugging reasons - and and forget about the loop around it. Then you can either click some hundred time on the "OK"-button or try getting a "Crtl-W" between the alert()s. If this happens in development, it's okay, you know what to do. But if a normal user is confronted with this, the only solution may be killing the process loosing the opened tabs. So the alert()s ought to be only modal within the tab. But that's another bug, I think.

All modality should be per tab, *if* that.

The JS modal alerts is covered in bug 59314. As for the other modal dialogs (namely the prefpane), I think there are plans to de-modalize them and perhaps even move them into tabs. At the very least, I don't think this bug should be fixed because it removes control from the user and we don't have any modal dialogs that need to be modal.