A few days ago, Alan Lepofsky told you how Lotus made it easy for you to get thin in 2008. It was a post about how we added shortcut keys of CTRL+2, to close the sidebar, CTRL+3 to make it thin and CTRL+4 to open it.
I did indeed pay attention to your reponses there. First of all, yes, we are almost out of shortcut combos that can apply across the entire platform. That is one of the challenges of being the "mother of all integration clients." (I am referring to the client itself, not me, although sometimes I feel that it's synonomous...)
While Nathan's suggestion of using CTRL+> works in left-to-right languages, it becomes completely counter-intuitive in Right-to Left languages (we generally change mnemonics per language, but not the shortcut keys.) So that is how we ended up with the CTRL+2, 3, and 4.
THE PLOT THICKENS, however. Some folks responded that certain key combinations did not work and/or crashed the client. So I investigated by testing it myself. I discovered that CTRL+2 does NOT work in the Symphony word processor or presentation tool because that key combo is already being used to change selected text to double spacing. Thus, I embarked on a mission to find a key combo that pertains across the client for "close the sidebar". CTRL+5 was also already taken by the same editors to make text 1.5 spaced.
Sigh. Thus, I entered an SPR (Software problem report = bug report) to change CTRL+2 to CTRL+0. 0 because Zero is nothing, as in, sidebar closed. I realize it might be more difficult to remember-- CTRL+3, CTRL+4 and then CTRL+0. But that's about all I had to work with. You can always ignore them and use the menus, or click the arrow in the middle of the sidebar.
But now you know the rest of the story :)