https://marco.org/2009/09/03/what-bothers-me-most-about-snow-leopard-is-this
What bothers me most about Snow Leopard is this simple indicator that shows that I’ve just moved to a different virtual desktop with Spaces using the convenient Ctrl+arrow keyboard shortcut.
Not that there’s anything wrong with the indicator itself, but because its continued presence means that I’m about to be mildly inconvenienced.
A significant portion of the times that I switch Spaces with the keyboard, this icon gets stuck on screen and it won’t release its keyboard capture. Other keyboard commands do absolutely nothing until I launch Activity Monitor (entirely using the mouse, which is incredibly frustrating) and force-quit the Dock process.
This was one of two annoying bugs in the last developer-preview build before Snow Leopard’s release. They fixed the other one, but this remains.