for that one guy who has a mouse but for some reason it doesnt have a scroll wheel

src/import/LauncherView.lua

@@ -124,12 +124,48 @@ function LauncherView.detach(imp)
   Kit.clearCaches()
 end
 
+local function markNoDrag(imp, x, y, w, h)
+  if Kit.blockClicks then return end
+  local t = imp._noDragRects
+  if not t then t = {}; imp._noDragRects = t end
+  local n = (imp._noDragN or 0) + 1
+  imp._noDragN = n
+  local r = t[n]
+  if not r then r = {}; t[n] = r end
+  r.x, r.y, r.w, r.h = x, y, w, h
+end
+
+local function noDragAt(imp, x, y)
+  local rects = imp._noDragRects
+  for i = 1, imp._noDragN or 0 do
+    if inRect(rects[i], x, y) then return true end
+  end
+  return false
+end
+
+local function armMouse(imp, x, y)
+  if noDragAt(imp, x, y) then
+    imp._clickPt = { x = x, y = y }
+    return
+  end
+  local shielded = imp._modalUpNow
+  imp._mouseAt = {
+    x = x, y = y,
+    region = not shielded and tabScrollMax(imp) > 0
+      and inRect(imp._tabRegionRect, x, y) or false,
+    page = not shielded and (imp._pageScrollMax or 0) > 0 or false,
+  }
+  Kit.dragBegin(x, y)
+end
+
 -- ---------------------------------------------------------------- input
--- The kit is polled, not evented: update() samples the mouse and turns a
--- rising edge into a click point that the next draw consumes.  Host-forwarded
--- mousepressed stays unused, exactly as before, so Android's synthesized
--- mouse path cannot double-fire a tap (#553) -- the dedup window below is the
--- other half of that guarantee.
+-- The kit is polled, not evented: update() samples the mouse.  A press arms
+-- a drag that scrolls like a finger, and the click dispatches on RELEASE so
+-- the drag can disqualify it, exactly like the touch path below; only the
+-- cartridge (which owns its own spin-drag) keeps the press-down click.
+-- Host-forwarded mousepressed stays unused, exactly as before, so Android's
+-- synthesized mouse path cannot double-fire a tap (#553) -- the dedup window
+-- below is the other half of that guarantee.
 function LauncherView.update(imp, dt)
   if not imp._flex then return end
   if imp._launchFade then return end
@@ -154,7 +190,39 @@ function LauncherView.update(imp, dt)
     if not touching and now >= (imp._suppressMouseUntil or 0)
         and now >= (imp._suppressClickUntil or 0) then
       local mx, my = love.mouse.getPosition()
-      imp._clickPt = { x = mx, y = my }
+      armMouse(imp, mx, my)
+    end
+  elseif down and imp._mouseAt then
+    local start = imp._mouseAt
+    local mx, my = love.mouse.getPosition()
+    local ddx, ddy = mx - start.x, my - start.y
+    if ddx * ddx + ddy * ddy > TAP_SLOP2 then
+      start.dragged = true
+    end
+    if start.dragged then
+      local last = start.lastY or start.y
+      local move = -(my - last)
+      if move ~= 0 and start.region then
+        local at, leftover = Kit.scrollHandoff(tabScrollAt(imp),
+          tabScrollMax(imp), move)
+        setTabScroll(imp, at)
+        move = leftover
+      end
+      if move ~= 0 and start.page and (imp._pageScrollMax or 0) > 0 then
+        local at, leftover = Kit.scrollHandoff(imp._pageScroll or 0,
+          imp._pageScrollMax, move)
+        imp._pageScroll = at
+        move = leftover
+      end
+      if move ~= 0 then Kit.dragAdd(move) end
+    end
+    start.lastY = my
+  elseif not down and imp._mouseAt then
+    local start = imp._mouseAt
+    imp._mouseAt = nil
+    Kit.dragEnd()
+    if not start.dragged then
+      imp._clickPt = { x = start.x, y = start.y }
     end
   end
   imp._prevMouseDown = down
@@ -233,10 +301,12 @@ function LauncherView.clickAt(imp, x, y)
   imp._clickPt = { x = x, y = y }
 end
 
--- Event-driven click: a macOS trackpad tap delivers press+release inside one
--- frame, so update()'s love.mouse.isDown poll never sees it.  Mint the click
--- from the press event under the poll's own suppression rules, and mark the
--- press seen so the poll cannot mint a second one when isDown does catch it.
+-- Event-driven press: a macOS trackpad tap delivers press+release inside one
+-- frame, so update()'s love.mouse.isDown poll never sees it.  Arm the drag
+-- from the press event under the poll's own suppression rules -- the poll's
+-- release branch then mints the tap, still within the same frame for a
+-- one-frame tap -- and mark the press seen so the poll cannot arm a second
+-- one when isDown does catch it.
 function LauncherView.mousepressed(imp, x, y)
   if not imp._flex then return end
   local now = love.timer.getTime()
@@ -245,7 +315,7 @@ function LauncherView.mousepressed(imp, x, y)
       or now < (imp._suppressClickUntil or 0) then
     return
   end
-  imp._clickPt = { x = x, y = y }
+  if not imp._mouseAt then armMouse(imp, x, y) end
   imp._prevMouseDown = true
 end
 
@@ -495,6 +565,7 @@ end
 
 local function cartridgeButton(imp, x, y, w, h, key, version, gameName, action)
   local state = cartridgeState(imp, version)
+  markNoDrag(imp, x, y, w, h)
   local focused = Kit.focusable(key, x, y, w, h)
   local hot = Kit.hover(x, y, w, h)
   local active = state.active
@@ -4868,13 +4939,15 @@ function LauncherView.draw(imp)
   Kit.beginFrame(mx, my, click ~= nil, imp._wheelY or 0)
   imp._clickPt = nil
   imp._wheelY = 0
+  imp._noDragN = 0
 
   Theme.field()
 
   -- Everything from here to buildModals sits UNDER any open modal, so the
   -- whole stage draws shielded (no clicks, no hover, no focus ring) while
   -- one is up; buildModals lowers the shield for the modal's own controls.
-  Kit.blockClicks = modalUp(imp)
+  imp._modalUpNow = modalUp(imp)
+  Kit.blockClicks = imp._modalUpNow
 
   local step = Kit.scrollStep(m.s)
   do

src/ui/kit/Kit.lua

@@ -918,16 +918,58 @@ function Kit.rowsThatFit(h, rowH, gap, minRows, maxRows)
   return math.max(minRows or 1, math.min(maxRows or 99, per))
 end
 
+Kit.dragX = nil
+Kit.dragY = nil
+Kit.dragAccum = 0
+
+function Kit.dragBegin(x, y)
+  Kit.dragX, Kit.dragY, Kit.dragAccum = x, y, 0
+end
+
+function Kit.dragAdd(dy)
+  if Kit.dragX then Kit.dragAccum = Kit.dragAccum + (dy or 0) end
+end
+
+function Kit.dragEnd()
+  Kit.dragX, Kit.dragY, Kit.dragAccum = nil, nil, 0
+end
+
+local function dragOriginIn(x, y, w, h)
+  if not Kit.dragX then return false end
+  local x1, y1, x2, y2 = x, y, x + w, y + h
+  local c = Kit._clipRect
+  if c then
+    x1, y1 = math.max(x1, c.x), math.max(y1, c.y)
+    x2, y2 = math.min(x2, c.x + c.w), math.min(y2, c.y + c.h)
+  end
+  return Kit.dragX >= x1 and Kit.dragX <= x2
+    and Kit.dragY >= y1 and Kit.dragY <= y2
+end
+
 -- Mouse wheel over a paginated list turns PAGES.  The wheel still has to do
 -- something (users expect it), but it moves a bounded page index rather than
 -- driving a pixel offset, so there is no scroll state and no interpolation.
 function Kit.wheelPage(x, y, w, h, page, total, perPage)
-  if Kit.blockClicks or (Kit.wheelY or 0) == 0 then return page end
-  if not Kit.hit(x, y, w, h) then return page end
+  if Kit.blockClicks then return page end
   local pages = math.max(1, math.ceil(total / math.max(1, perPage)))
-  local moved = Theme.clamp((page or 1) + (Kit.wheelY > 0 and -1 or 1), 1, pages)
-  Kit.wheelY = 0
-  return math.floor(moved)
+  local out = page
+  if (Kit.wheelY or 0) ~= 0 and Kit.hit(x, y, w, h) then
+    out = math.floor(Theme.clamp((out or 1) + (Kit.wheelY > 0 and -1 or 1),
+      1, pages))
+    Kit.wheelY = 0
+  end
+  local acc = Kit.dragAccum or 0
+  if acc ~= 0 and dragOriginIn(x, y, w, h) then
+    local stepPx = math.max(1, math.floor((h or 0) / 2))
+    local flips = acc >= 0 and math.floor(acc / stepPx)
+      or -math.floor(-acc / stepPx)
+    if flips ~= 0 then
+      local want = (out or 1) + flips
+      out = math.floor(Theme.clamp(want, 1, pages))
+      Kit.dragAccum = out ~= want and 0 or acc - flips * stepPx
+    end
+  end
+  return out
 end
 
 function Kit.scrollExtent(contentH, viewH)

tests/engine/launcher_scroll_test.lua

@@ -300,6 +300,88 @@ LauncherView.draw(edgeImp)
 check((edgeImp._tabScroll.skins or 0) > 0,
   "which reaches the tab region even though the cursor is below it")
 
+Kit.blockClicks = false
+Kit._clipRect = nil
+Kit.wheelY = 0
+Kit.mouseX, Kit.mouseY = 400, 400
+Kit.dragBegin(50, 50)
+Kit.dragAdd(120)
+local pg = Kit.wheelPage(0, 0, 100, 100, 1, 100, 10)
+eq(pg, 3, "a drag that crossed two half-heights turns two pages")
+eq(Kit.dragAccum, 20, "and keeps the remainder for the next flip")
+Kit.dragAdd(-140)
+pg = Kit.wheelPage(0, 0, 100, 100, pg, 100, 10)
+eq(pg, 1, "dragging back down returns those pages")
+eq(Kit.dragAccum, -20, "with the remainder's sign preserved")
+Kit.dragAdd(-80)
+pg = Kit.wheelPage(0, 0, 100, 100, pg, 100, 10)
+eq(pg, 1, "a drag past the first page clamps to it")
+eq(Kit.dragAccum, 0, "and drops the pile-up so reversing is instant")
+Kit.dragAdd(200)
+pg = Kit.wheelPage(200, 200, 100, 100, pg, 100, 10)
+eq(pg, 1, "a drag that began outside the list is not the list's")
+eq(Kit.dragAccum, 200, "and its travel stays queued")
+Kit.dragEnd()
+eq(Kit.dragAccum, 0, "releasing the button retires the gesture")
+
+window(360, 780)
+local mouseImp = skinLauncher(12)
+LauncherView.draw(mouseImp)
+LauncherView.draw(mouseImp)
+local mreg = mouseImp._tabRegionRect
+local mmax = mouseImp._tabScrollMax.skins
+check(mmax > 0, "the mouse-dragged panel has travel")
+local mdown = false
+love.mouse.isDown = function() return mdown end
+
+pointer(mreg.x + 20, mreg.y + 40)
+mdown = true
+LauncherView.update(mouseImp, 0.016)
+check(mouseImp._clickPt == nil,
+  "a press over a scrollable region mints no click")
+check(mouseImp._mouseAt ~= nil, "it arms a drag instead")
+pointer(mreg.x + 20, mreg.y + 40 - 200)
+LauncherView.update(mouseImp, 0.016)
+eq(mouseImp._tabScroll.skins, math.min(200, mmax),
+  "dragging the held mouse scrolls the panel by its travel")
+eq(mouseImp._pageScroll or 0, 0,
+  "while the panel still has travel, the page waits")
+pointer(mreg.x + 20, mreg.y + 40 - 200 - mmax * 2)
+LauncherView.update(mouseImp, 0.016)
+eq(mouseImp._tabScroll.skins, mmax,
+  "a longer mouse drag reaches the panel's bottom")
+check((mouseImp._pageScroll or 0) > 0, "and spills into the page from there")
+mdown = false
+LauncherView.update(mouseImp, 0.016)
+check(mouseImp._clickPt == nil, "a released drag is not a click")
+check(mouseImp._mouseAt == nil, "and the gesture is retired")
+
+pointer(mreg.x + 20, mreg.y + 40)
+mdown = true
+LauncherView.update(mouseImp, 0.016)
+check(mouseImp._clickPt == nil, "a fresh press still holds its click back")
+mdown = false
+LauncherView.update(mouseImp, 0.016)
+check(mouseImp._clickPt ~= nil,
+  "press and release without travel is still a tap, on release")
+mouseImp._clickPt = nil
+
+LauncherView.draw(gameImp)
+LauncherView.draw(gameImp)
+check((gameImp._noDragN or 0) > 0, "the game tab publishes its cartridge rect")
+local cart = gameImp._noDragRects[1]
+pointer(cart.x + cart.w / 2, cart.y + cart.h / 2)
+mdown = true
+LauncherView.update(gameImp, 0.016)
+check(gameImp._clickPt ~= nil,
+  "a press on the cartridge clicks at once so its own spin-drag still owns "
+    .. "the gesture")
+check(gameImp._mouseAt == nil, "and never arms the scroll drag")
+gameImp._clickPt = nil
+mdown = false
+LauncherView.update(gameImp, 0.016)
+love.mouse.isDown = nil
+
 local function read(path)
   local f = assert(io.open(path, "r"))
   local src = f:read("*a")