timo How about a help page listing the keyboard shortcuts? It shouldn't take long to bang out a list. 🙂
You say hover works, but I don't see any keyboard shortcuts in tooltips, and no tooltips at all in the sidebar. So the only way to discover sidebar navigation shortcuts, as far as I can tell, is to stumble upon them through trial and error. If I wasn't such a determined keyboard commando, I would never have found out that CTRL+T takes you to Timeline, and CTRL+OPT+T takes you to Tags — but only if the sidebar already has focus. So there's actually no app-wide shortcut for navigating to these areas. It's also counter-intuitive for Mac users that these shortcuts remain CTRL combinations instead of CMD combinations.