bugmacmacosui
I have recently noticed that some of my windows have weird looking corners. It's like they are missing dark pixels right on the edge.
It doesn't always happen, some windows seem to be 'immune' – one example would be Messages, which is the window in the middle.
I'm running OS X 10.9.3.
Most applications have never had a menu item for it. I don't know why Finder and Terminal do though.
⌘` should cycle through windows by default, but if it doesn't, check if the shortcut has been disabled or changed in System Preferences.
One way to keep emacs running stable for a long time is running it as a separate GUI app. I installed GNU Emacs for Mac OSX and it runs without any redraw issue. It will pick up your normal .emacs configuration and if you do not like the GUI elements like the toolbar you can hide them on startup in the variable default-frame-alist.
Best Answer
After the OS X Mavericks v10.9.4 Update, window corners have returned to their previous glory. Update notes don't mention any issue of this kind, so I guess it might have been fixed as a side effect of running the system updater.
EDIT: Aaand the corners are ugly again. It's really weird.