In order to reduce window clutter, improve functionality, and save time, I am proposing a systemwide hierarchical tree view be used in the panel (not by default, but at the behest of the user, of course). This tree is best viewed in a vertical orientation, thus the panel should be in a vertical position on either the left or the right side for this view.
Consider this scenario:
The user is browsing the internet in Firefox and wants to open a link in a new tab. If the user does so, he/she will not see the new tab in the tree (since the tab is inside a window and the first tab is highlighted, so it is the one that appears in the tree). If the user continues to open new tabs, it will become difficult to find a tab later because of the way they are organized.
The only viable way to organize tabs then, is to group them in a hierarchical manner. It would be difficult to do this with tabs, and it would be difficult to do this with the bottom panel, the task-bar, or the dock. However, it would be easy to organize and keep track of windows, browser or otherwise in a tree view. For me and I'm sure many others, this method has already improved internet browsing with Firefox Add-ons like Tree style tab.