DouKaku?

| file font nLines cr sp goNextPage goPrevPage findNext prevLine |
file := FileStream fileNamed: 'in.txt'.

font := TextStyle defaultFont.
cr := Character cr.
sp := Character space.
nLines := Display height // (font height + font descent).

goNextPage := [nLines timesRepeat: [file nextLine]].
prevLine := [file binary. [file position = 0 or: [file back = 13]] whileFalse. file ascii].
goPrevPage := [nLines timesRepeat: [prevLine value]].
findNext := [:pattern | pattern notEmpty ifTrue: [file upToAll: pattern]. prevLine value].

[   | string |
    string := String streamContents: [:ss |
        | position |
        position := file position.
        nLines timesRepeat: [
            file nextLine ifNotNilDo: [:line | ss nextPutAll: line].
            file peek ifNotNil: [ss cr]].
        file position: position].
    Display fillWhite.
    string asDisplayText display.
    [Sensor keyboardPressed] whileFalse.
    Sensor keyboard caseOf: {
        [$q] -> [file close. ^World restoreDisplay].
        [$g] -> [file reset].
        [$G] -> [file setToEnd].
        [sp] -> [goNextPage value].
        [$f] -> [goNextPage value].
        [$b] -> [goPrevPage value].
        [cr] -> [file nextLine].
        [$e] -> [file nextLine].
        [$y] -> [prevLine value].
        [$/] -> [findNext value: (FillInTheBlank request: 'pattern:')]
    } otherwise: []
] repeat