This recent change to the search function has been a big headache to me as well and very aggravating. Ever since the change, I'm constantly forgetting that the scope defaults to selected if you have a line of text selected, even if it's a single word, which seems counter-intuitive to me. It makes more sense to keep it defaulted to global unless multiple lines are selected (or just keep it global no matter what). I very rarely search within selected text myself, but maybe it's more common than I think. The method simshaun proposed actually makes the most sense, for me anyway - I typically only search withing selected text when I'm doing a replace.
EDIT: Never mind, looks like it's now fixed in build 5917. Global select is default unless multiple lines are selected. Yeah!
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