Cannot Type in Launchpad
If I activate Launchpad on my MacBook Pro, I can type in the first few letters of an application's name to find its icon. On my iMac, it doesn't take the keyboard input at all.
It is too hard to find the application by inspection, because Launchpad produces a visual jungle of icons spread over many pages, all applications have the same importance (uninstall is just as important to Launchpad as my word processor is), organizing them is manual and tedious, and "folders" of icons can only go one level deep. So I want to use Launchpad's command-line feature to find applications.
How can I fix Launchpad to enable the typing feature?
iMac, OS X Mountain Lion (10.8.2), Mid-2007