viewport in Bubbles v2

A scrollable window over a block of text. Return to the main skill for the shared component contract and focus rules.

Create it on the first tea.WindowSizeMsg and resize it on later ones (examples/charmed-bubbles/viewport/main.go):

// examples/charmed-bubbles/viewport/main.go
case tea.WindowSizeMsg:
    if !m.ready {
        m.vp = viewport.New(viewport.WithWidth(msg.Width), viewport.WithHeight(msg.Height-headerHeight))
        m.vp.MouseWheelEnabled = true
        m.vp.SoftWrap = true
        m.vp.SetContent(content)
        m.ready = true
    } else {
        m.vp.SetWidth(msg.Width)
        m.vp.SetHeight(msg.Height - headerHeight)
    }

// View needs v.MouseMode set for the wheel to reach the viewport.

ScrollPercent(), AtTop(), AtBottom(), GotoTop(), GotoBottom(), SetYOffset(n), ScrollDown(n). SoftWrap wraps long lines; with it off the viewport scrolls horizontally (ScrollLeft, ScrollRight). SetHighlights([][]int) plus HighlightNext and HighlightPrevious implement search hits. LeftGutterFunc draws line numbers or markers. FillHeight pads short content to the full height.