Just in case someone isn't already using this handy feature, I'd like to call attention to the ability to dock multiple panes in a single pane with tabs.  I just figured this out recently (I'm slow) when I found I was

running out of horizontal space after adding the Tags and Favorites panes next to my existing Forms pane.

 

Having three or more panes combined in one saves a lot of space while keeping what you need in easy reach.  Here's what my current set up looks like:

 

 

All you have to do is drag a pane or detached grid over the existing pane and drop it in place when the pane changes color.