Or another more funny solution would be using AngelScript.
You would only need to create a script that does something like:
// toggle tab usage
bool use = editor->GetUseTabs();
editor->SetUseTabs(!use);
And then register a menu with it along with an accelerator.
The only (minor?) problems with it are:
-*UseTabs() function are not registered, you'll need to register it in scriptbindings.cpp, and recompile C::B.
-Can a script create a new menu entry with an accelerator?
-The script would be loaded once, or it would be loaded each time the function is needed?