Side pane

[GoogleCodeExporter]

Describe the feature you want implemented.
A side pane which can be toggled on or off and have different type of content.

As a first step it would house YouTube content which will display either 
general YouTube stuff such as trending stuff, or general user stuff if logged 
in such as own videos and recently watched, or track specific content if a 
YouTube track is selected such as similar and comments.

The equalizer can be moved here, as can the playlist generator. It could also 
house a bookmark manager and a meta data cleaning tool.

Plugins could also add content to the side panel.

Describe why you think that this feature is needed.
We need to expand the feature set of Stoffi but without adding to many new 
dialogs, settings, etc. By defining a side pane with different content we can 
make such new features easy to discover, customize the layout of controls 
inside the pane but provide a consistent way of accessing them via the menu 
button.

Are there any other projects that inspired you?
The button should be a mash between the "Preview panel" button in Explorer and 
the "Change your view" button's arrow and menu. When the button is clicked it 
will toggle the visibility of the side pane. When the arrow is clicked it will 
toggle the menu from which the user can choose the content that should be shown 
inside the side pane.

Original issue reported on code.google.com by ephracis on 21 Apr 2012 at 9:30