Fancy completion all over Emacs, not just for buffers and files. https://github.com/DarwinAwardWinner/ido-completing-read-plus

Ryan C. Thompson e802c9c9c9 Make completing-read-ido-ubiquitous explain fallbacks vor 10 Jahren
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README.md c430dd331d Improve some documentation vor 10 Jahren
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ido-ubiquitous.el e802c9c9c9 Make completing-read-ido-ubiquitous explain fallbacks vor 10 Jahren

README.md

ido-ubiquitous

Gimme some ido... everywhere! This pacakge replaces stock emacs completion with ido completion wherever it is possible to do so without breaking things.

Get it from http://marmalade-repo.org/packages/ido-ubiquitous

Note that ido-ubiquitous is not enabled for org mode or magit mode, because those modes have their own built-in support for ido, which you should enable instead. Also, to enable ido for all file and buffer completion, customize ido-everywhere.