So I've had an odd problem with Domino Designer lately. The centre panel - the one with the links to create a new app, open and app. You know, the panel that's there that we never use or really look at. It disappeared.
So my Designer client had a hole in the middle. We don't use that panel anyway, do we? We it turns out I do. Not to use the links there (except to occasionally create a new app). 
But it is the thing that keeps the tabs in place. In order to keep things under control, I try to close the tabs I open in Designer. If you don't have that panel, the last tab you have before you close is all the way over on your right, not on the left. So I forget to close it. And I end up working on an element I didn't mean to. Basically it messed with my flow.
I struggled a bit. I don't know what did it. First I thought it was when I added Facebook to my Wildfire stream. I tried a repair install, then an uninstall and reinstall. Nope, it wouldn't come back. I deleted my workspace folder - taking out all my working sets et al. That got it back once. If I closed and re-opened Designer it was gone again. I saved the default perspective with a different name. When that panel disappeared, calling my saved variant didn't bring it back.
That panel is called "Home". It's not an option to add if you look in the Eclipse view or the perspectives to add. If you add one called "Home" that's the one for the Notes client.
I finally called Lotus ICS Support. There is a menu item called "Help" (don't be deceived by the name - it no longer offers actual help). Click "Home" and that panel returns. So I get my Home panel returned.
Now if we could get actual Help from the Help menu. You know, the bit like in 8.5.
Cheers,
Brian