Find bar opens when typing in textbox
From MozillaZine Knowledge Base
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If you try typing in a text box on certain sites before the page is finished loading the focus can be confused and not respond as if you're focused in a text field. Waiting for the page to finish loading or refreshing the page can resolve the issue.
Opening multiple windows using a desktop or quick launch shortcut can cause a focus bug which breaks clipboard tasks, and other focus-dependent tasks, especially in text fields (Bug 220900). Minimizing the windows and maximizing them will usually reset focus once this issue is encountered. To avoid seeing this issue altogether, launch new windows using the New Window menu item, or shortcut (Ctrl+N) or add a New Window button to your toolbar.
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