How do I disable multi line pasting into a single line text area?

Hello,

This is not a bug. This is an on purpose change (bug 406062) to make pasting addresses into mapping sites easier. The feature has existed before, but was disabled, and existed as a lifehacker firefox tip (as well as a 'firefox tip' on countless other sites). You obviously want to change it back to what it was before, '1'. There's also a detailed list of possible editor.singleLine.pasteNewlines preferences in case you prefer another one of the 6 options.