Problem: When books are transcluded into many pages, it is difficult to search text in them. For example, if I want to search Ajax in the Iliad, I must open 24 transclusions (Iliad/Canto I, Iliad/Canto II, etc.) and make a text search in every page; another solution, but which is barely known even by contributors of Wikisource, would be using the advanced search, namely its field "Subpages of this page". To remedy this, some contributors create a new page with the full text of the book : Iliad/Full text. I think it would be more useful to provide a search bar in every page of the main namespace which allows to find text in the current page or in all subpages.
Proposed solution: Provide a search bar on every page of the main namespace, giving results in the current page or in the whole book. In a word, this search bar would search text exactly in the same pages as the ones exported by the Export button. More precisely, it might be inserted next to the Export button, at the very top of the page, and may function in a similar way: if the Export button enables to export only the current page, the search bar reads « Search in this page » and gives the same results as Ctrl+F/Cmd+F; but when the Export button enables to export the whole book, the search bar reads « Search in full book ».
Who would benefit: ::Readers: on French Wikisource, the full text page of famous books (like Candide by Voltaire) are more read than the individual transclusions, because readers consult these books on Wikisource mainly for full text search.
Editors: we could save time if we stopped creating full text pages, which often have problems (too many templates, broken links, etc.)
More comments: Idea of improvement : enabling regular expressions in this search bar (which is impossible with Ctrl+F: it would then justify the presence of this search bar in every page).
