Hotkey to show hidden files and folders in File Open dialog?
⌘ CMD+⇧ SHIFT+. reveals hidden files in Finder and Open/Save dialogs.

If you are using an AZERTY keyboard, you'll need to press fn too, so ⇧ SHIFT is taken into consideration as you already need it to make the ..



You can also press ⌘ CMD+⇧ SHIFT+G and type the path to the hidden folder, just like in Terminal (⇥ TAB autocompletion also works).

Editing hidden files can be dangerous if you don't know what you're doing.