This is still a problem in Mountain Lion.
You can have a Toolbar without a Sidebar, but
you can't have a Sidebar without a Toolbar.
Why would they grey out "Show Sidebar" when the Toolbar is not shown?
What is the great benefit that justifies millions of hours wasted
in figuring out how to show the sidebar?
For those whom are still confused, I have found the first time you show sidebar it doesn't seem to show (I think it does, but you have pull it out with the mouse). So usually I just hide it, then show it again. So keystrokes would be:
command option T to show toolbar
command option S to show sidebar, but its kind of hidden still
command option S to hide sidebar
command option S to show sidebar and this time it shows.
Does anyone know if you still have show the sidebar three times in Mountian Lion?
Starting in 10.1 (at least) there is an oval "pill" button in upper right corner of Finder window title bars.
It is the hide/show toolbar (and sidebar) button. You can see it in 10.1 - 10.6 screenshots here.
The button's function and loss are discussed here:
I skipped 10.7 and 10.8, so didn't feel the loss until 10.9.
Sigh. Com-Opt-T and Com-Opt-S are ok (when they work). But I still want that button back!
Here's another thread on this: