diff --git a/LANGUAGE.md b/LANGUAGE.md
index 3efda29a..9a1221d9 100644
--- a/LANGUAGE.md
+++ b/LANGUAGE.md
@@ -446,14 +446,20 @@ applies to both:
 
   Each reports with `on-change` and `event.value`, and plays `sound="..."` (or "click") through
   the program's `ui_sounds`.
+- **Popovers, tooltips and bars.**
+  - `<div popover on-close="...">` sits absolutely in its parent and draws on the top layer. While
+    it is up, the pointer and Tab stay inside it, and a press outside it or Esc closes it.
+  - `title="..."` shows a tooltip (`.ui-tooltip`) after the pointer rests for half a second.
+  - `<progress value max>` and `<meter value min max>` fill (`.ui-fill`) as far as their value.
 - **Natives** are for what markup cannot say. `ui_native("minimap", measure, draw)` makes
   `<minimap>` an element the program draws itself, laid out and styled like any other. It reports
   with `ui_fire(n, "change", value)` and reads its attributes with `ui_attr` / `ui_attr_on`.
 - **Renderers.** `ui_backend(b)` takes any renderer with `rect`, `text` and `measure`, and uses
   `round`, `ring`, `image`, `nine`, `clip`, `scale` and `now` when it has them.
-  `import "ludic.ui/render3d.ludic"` and `ui_render3d()` draw with render3d's overlay:
-  - images by path, cells of an atlas named with `ui_atlas(prefix, texture, cols, names)` as
-    `<img src="prefix:name">`, and nine-slices for `border-image`;
+  Importing `ludic.ui/render3d.ludic` makes render3d's overlay the renderer:
+  - images by path, and cells of an atlas named with `ui_atlas(prefix, texture, cols, rows,
+    names)` as `<img src="prefix:name">` (or `prefix:12`);
+  - nine-slices for `border-image`;
   - a scale from the screen's height (`ui_render3d_scale` for the player's interface size).
 
   `ui_translator(fn)`, `ui_sounds(fn)` and `ui_clock(fn)` hand the runtime the program's
diff --git a/changes/defaults-views-templates.md b/changes/defaults-views-templates.md
index 2cd6b82f..e5a1e6ed 100644
--- a/changes/defaults-views-templates.md
+++ b/changes/defaults-views-templates.md
@@ -48,6 +48,9 @@ The runtime is a UI framework, not only a template engine:
 - more CSS: `rgba()`/`#rrggbbaa`, `border-radius`, `outline`, `box-shadow`, `background-image`,
   `border-image`, group `opacity`, `@keyframes` / `animation` / `transition`;
 - HTML mixed content, and boolean attributes;
+- `popover` (a top layer that keeps the pointer and keys, with light dismissal), `title` tooltips,
+  and `<progress>` / `<meter>`;
+- importing `ludic.ui/render3d.ludic` installs the backend, and atlases take rows;
 - hooks for the program's language, sounds and clock.
 
 render3d gains `tex_width` / `tex_height`, and the XML reader keeps text runs among elements in
@@ -63,3 +66,6 @@ Also:
 - An index is evaluated before the slice's elements are read. A `xs[f()]` whose `f` grew `xs`
   read stale memory.
 - A runtime error names the file its expression is in, not the program's.
+
+Two declarations with one name (a package's private global and a program's, say) are reported as
+such before type checking. They used to surface as a page of type errors about the wrong type.
diff --git a/examples/library/ui_popover.ludic b/examples/library/ui_popover.ludic
new file mode 100644
index 00000000..ef1af5af
--- /dev/null
+++ b/examples/library/ui_popover.ludic
@@ -0,0 +1,59 @@
+# ui_popover.ludic — HTML's popover and progress in ludic.ui: a button opens a popover of verbs, the
+# keyboard stays inside it, a press outside or Esc closes it, and a progress bar fills to its value.
+import "ludic.ui"
+import "ui_popover_parts/Verbs.ludic"
+program UiPopover {
+  numbers float
+  function frame(i: UiInput) -> UiNode {
+    ui_input(i)
+    ui_show("Verbs", null, 0.0, 0.0, 400.0, 400.0)
+    let root: UiNode = ui_nodes("Verbs", null)
+    ui_place(root, 0.0, 0.0, 400.0, 400.0)
+    return root
+  }
+  function click(x: float, y: float) -> void {
+    let d = new UiInput
+    d.x = x
+    d.y = y
+    d.down = true
+    frame(d)
+    let u = new UiInput
+    u.x = x
+    u.y = y
+    frame(u)
+  }
+  function said(root: UiNode) -> string {
+    let page = root.children[0]
+    return page.children[len(page.children) - 1].text
+  }
+  entry {
+    ui_backend(new UiBackend)
+    var root = frame(new UiInput)
+    let cell = root.children[0].children[0]
+    click(cell.x + 2.0, cell.y + 2.0)
+    root = frame(new UiInput)
+    let tab = new UiInput
+    tab.tab = true
+    frame(tab)
+    frame(tab)
+    root = frame(tab)
+    let enter = new UiInput
+    enter.enter = true
+    root = frame(enter)
+    root = frame(new UiInput)
+    let first = said(root)
+    click(cell.x + 2.0, cell.y + 2.0)
+    root = frame(new UiInput)
+    let opened = said(root)
+    click(390.0, 390.0)
+    root = frame(new UiInput)
+    let outside = said(root)
+    click(cell.x + 2.0, cell.y + 2.0)
+    let esc = new UiInput
+    esc.escape = true
+    frame(esc)
+    root = frame(new UiInput)
+    let bar = root.children[0].children[1]
+    print(`{first} | {opened} | {outside} | {said(root)} | fill {int(bar.children[0].cw)} of {int(bar.cw)}`)
+  }
+}
diff --git a/examples/library/ui_popover_parts/Verbs.lss b/examples/library/ui_popover_parts/Verbs.lss
new file mode 100644
index 00000000..ae965783
--- /dev/null
+++ b/examples/library/ui_popover_parts/Verbs.lss
@@ -0,0 +1,3 @@
+.page { width: 300px; height: 200px; gap: 4px }
+.verbs { top: 40px; left: 10px; width: 120px }
+progress { width: 200px }
diff --git a/examples/library/ui_popover_parts/Verbs.ludic b/examples/library/ui_popover_parts/Verbs.ludic
new file mode 100644
index 00000000..090f1929
--- /dev/null
+++ b/examples/library/ui_popover_parts/Verbs.ludic
@@ -0,0 +1,6 @@
+# Verbs.ludic - a grid cell that opens a popover of verbs
+component Verbs {
+  state open: bool = false
+  state used: string = "none"
+  state health: int = 30
+}
diff --git a/examples/library/ui_popover_parts/Verbs.xml b/examples/library/ui_popover_parts/Verbs.xml
new file mode 100644
index 00000000..34ec8bb4
--- /dev/null
+++ b/examples/library/ui_popover_parts/Verbs.xml
@@ -0,0 +1,11 @@
+<div class="page">
+  <button id="cell" on-click="set open = true">Axe</button>
+  <if test="{open}">
+    <div popover class="verbs" on-close="set open = false">
+      <button on-click="set used = 'drop'; set open = false">Drop</button>
+      <button on-click="set used = 'give'; set open = false">Give</button>
+    </div>
+  </if>
+  <progress value="{health}" max="{100}"/>
+  <p title="how much is left">{used} {open}</p>
+</div>
diff --git a/packages/ludic.ui/controls_build.ludic b/packages/ludic.ui/controls_build.ludic
index 2a606691..0b0a80c6 100644
--- a/packages/ludic.ui/controls_build.ludic
+++ b/packages/ludic.ui/controls_build.ludic
@@ -21,7 +21,21 @@ function ct_part(n: UiNode, cls: string, text: string) -> UiNode {
   }
   return p
 }
+# <progress value max> and <meter value min max>: a track with a fill as far as the value
+function ct_build_bar(n: UiNode) -> void {
+  n.dir = UI_ROW
+  let lo = Value.as_float(ui_attr(n, "min"))
+  var hi = Value.as_float(ui_attr(n, "max"))
+  if hi <= lo { hi = lo + 1.0 }
+  let fill = ct_part(n, "ui-fill", "")
+  fill.w_pct = Math.clamp((Value.as_float(ui_attr(n, "value")) - lo) / (hi - lo), 0.0, 1.0) * 100.0
+  push(n.children, fill)
+}
 function ct_build(n: UiNode) -> void {
+  if n.tag == "progress" or n.tag == "meter" {
+    ct_build_bar(n)
+    return
+  }
   n.dir = UI_ROW
   n.focusable = true
   let t = ui_attr_text(n, "type")
diff --git a/packages/ludic.ui/draw_order.ludic b/packages/ludic.ui/draw_order.ludic
index 189f995c..15a4d7b5 100644
--- a/packages/ludic.ui/draw_order.ludic
+++ b/packages/ludic.ui/draw_order.ludic
@@ -29,20 +29,20 @@ function fr_clip_pop() -> void {
 function fr_children(n: UiNode) -> void {
   var positioned = 0
   for i in 0 .. len(n.children) {
-    if n.children[i].pos == 0 { fr_draw(n.children[i]) } else { positioned += 1 }
+    if n.children[i].popover { push(pop_list, n.children[i]) } else if n.children[i].pos == 0 { fr_draw(n.children[i]) } else { positioned += 1 }
   }
   if positioned == 0 { return }
   var lo = 1000000
   var hi = -1000000
   for i in 0 .. len(n.children) {
-    if n.children[i].pos != 0 {
+    if n.children[i].pos != 0 and not n.children[i].popover {
       lo = Math.min(lo, n.children[i].z)
       hi = Math.max(hi, n.children[i].z)
     }
   }
   for z in lo .. hi + 1 {
     for i in 0 .. len(n.children) {
-      if n.children[i].pos != 0 and n.children[i].z == z { fr_draw(n.children[i]) }
+      if n.children[i].pos != 0 and not n.children[i].popover and n.children[i].z == z { fr_draw(n.children[i]) }
     }
   }
 }
diff --git a/packages/ludic.ui/elem.ludic b/packages/ludic.ui/elem.ludic
index eb6ef24b..4d7120e2 100644
--- a/packages/ludic.ui/elem.ludic
+++ b/packages/ludic.ui/elem.ludic
@@ -1,6 +1,6 @@
 # elem.ludic - an element made from its template: what kind of node its tag is, its id, classes
 # and attributes (kept for selectors, applied after every rule), its text, and its children
-const EL_BOXES: string = " col div section header footer nav main article aside ul ol li form box "
+const EL_BOXES: string = " col div progress meter section header footer nav main article aside ul ol li form box "
 const EL_TEXTS: string = " text span p label h1 h2 h3 h4 h5 h6 strong em small b i a option "
 function bd_elem(k: UiTpl, e: UiEnv, key: string) -> UiNode {
   ui_at = k.where
@@ -27,7 +27,7 @@ function bd_elem(k: UiTpl, e: UiEnv, key: string) -> UiNode {
   bd_kids(k.kids, e, key, n.children)
   if k.text != null { el_text(n, ui_tr(ui_eval_text(k.text, e))) }
   el_inline(n)
-  if k.tag == "input" or k.tag == "select" { ct_build(n) }
+  if k.tag == "input" or k.tag == "select" or k.tag == "progress" or k.tag == "meter" { ct_build(n) }
   return n
 }
 function el_kind(n: UiNode, tag: string) -> void {
@@ -61,6 +61,12 @@ function el_keep(n: UiNode, key: string, v: Val) -> void {
     for i in 0 .. len(parts) {
       if len(parts[i]) > 0 { push(n.classes, parts[i]) }
     }
+  } else if key == "popover" {
+    n.popover = true
+    n.pos = 2
+    push(n.akeys, key)
+    push(n.avals, s)
+    push(n.vals, v)
   } else if key == "tabindex" { n.focusable = s != "-1" } else if key == "hidden" { n.hidden = el_flag(v) } else if key == "disabled" { n.enabled = not el_flag(v) } else if key == "src" { n.src = s } else {
     if key == "enabled" { n.enabled = el_flag(v) }
     push(n.akeys, key)
diff --git a/packages/ludic.ui/focus.ludic b/packages/ludic.ui/focus.ludic
index 107adbca..7c9acfb1 100644
--- a/packages/ludic.ui/focus.ludic
+++ b/packages/ludic.ui/focus.ludic
@@ -27,7 +27,9 @@ function fc_move(step: int) -> void {
 # the keys, after the tree is laid out: moving, then acting on what has the focus
 function fc_keys(root: UiNode) -> void {
   fc_list = new []UiNode
-  fc_collect(root)
+  let top = pp_top(root)
+  if top != null and in_now.escape { ui_fire(top, "close", Value.null()) }
+  if top != null { fc_collect(top) } else { fc_collect(root) }
   let i = in_now
   if fc_find() < 0 { fc_autofocus() }
   let at = fc_find()
diff --git a/packages/ludic.ui/frame.ludic b/packages/ludic.ui/frame.ludic
index f78adc93..a909a33f 100644
--- a/packages/ludic.ui/frame.ludic
+++ b/packages/ludic.ui/frame.ludic
@@ -14,7 +14,11 @@ export function ui_show(screen: string, view: UiView, x: float, y: float, w: flo
   sc_update(root)
   fr_pointer(root)
   fc_keys(root)
-  if ui_be != null and ui_be.text != null { fr_draw(root) }
+  if ui_be != null and ui_be.text != null {
+    fr_draw(root)
+    pp_draw_top()
+    tt_draw(root)
+  }
   dv_after(screen, root)
   lc_run(screen)
   nt_fired_run()
diff --git a/packages/ludic.ui/index.ludic b/packages/ludic.ui/index.ludic
index a106124d..dd32cff5 100644
--- a/packages/ludic.ui/index.ludic
+++ b/packages/ludic.ui/index.ludic
@@ -19,6 +19,8 @@ import "controls_build.ludic"
 import "input.ludic"
 import "focus.ludic"
 import "scroll.ludic"
+import "popover.ludic"
+import "tooltip.ludic"
 import "life.ludic"
 import "tpl.ludic"
 import "tpl_lines.ludic"
diff --git a/packages/ludic.ui/link.ludic b/packages/ludic.ui/link.ludic
index 28dba679..194b94d3 100644
--- a/packages/ludic.ui/link.ludic
+++ b/packages/ludic.ui/link.ludic
@@ -1,6 +1,6 @@
 # link.ludic - each tag in a file that is not an element names a component: the file's own, an
 # unnamed import's exported one, or `as:Name` from the import called `as`
-const LK_OWN: string = " row button input select textarea spacer scroll img hr if else each slot state style component screen import let fragment template provide #text "
+const LK_OWN: string = " row button input select textarea progress meter spacer scroll img hr if else each slot state style component screen import let fragment template provide #text "
 function lib_link(f: UiFile, t: UiTpl) -> void {
   t.sheet = f.sheet
   if not lk_element(t.tag) {
diff --git a/packages/ludic.ui/node.ludic b/packages/ludic.ui/node.ludic
index 6fe7e884..cecd9108 100644
--- a/packages/ludic.ui/node.ludic
+++ b/packages/ludic.ui/node.ludic
@@ -103,5 +103,6 @@ export property UiNode {
   anim_loop: bool = false
   anim_alt: bool = false
   tr_dur: float = 0.0           # transition: how long a change of opacity takes
+  popover: bool = false         # drawn on the top layer; a press outside it or Esc closes it
 }
 
diff --git a/packages/ludic.ui/pointer.ludic b/packages/ludic.ui/pointer.ludic
index 8e94ee95..2b21a7e4 100644
--- a/packages/ludic.ui/pointer.ludic
+++ b/packages/ludic.ui/pointer.ludic
@@ -9,9 +9,14 @@ function fr_pointer(root: UiNode) -> void {
   let i = in_now
   fr_down_now = i.down
   let keys = new []string
-  fr_under(root, i.x, i.y, keys)
+  let top = pp_top(root)
+  var scope = root
+  if top != null { scope = top }
+  fr_under(scope, i.x, i.y, keys)
   fr_hover = keys
-  let hit = fr_hit(root, i.x, i.y)
+  tt_track(scope, i.x, i.y)
+  if top != null and pp_pointer(top) { return }
+  let hit = fr_hit(scope, i.x, i.y)
   if i.down and not in_was_down {
     fr_press_key = ""
     if hit != null {
diff --git a/packages/ludic.ui/popover.ludic b/packages/ludic.ui/popover.ludic
new file mode 100644
index 00000000..0ba0a3f4
--- /dev/null
+++ b/packages/ludic.ui/popover.ludic
@@ -0,0 +1,32 @@
+# popover.ludic - HTML's popover: `<div popover on-close="...">` sits where its position puts it
+# (absolutely, in its parent) and is drawn on the top layer, over everything. While one is up the
+# pointer and the keyboard are its: a press outside it, or Esc, closes it (on-close), and Tab
+# walks only its own controls.
+var pop_list: []UiNode = new []UiNode
+function pp_find(n: UiNode, out: []UiNode) -> void {
+  if n.popover {
+    push(out, n)
+    return
+  }
+  for i in 0 .. len(n.children) { pp_find(n.children[i], out) }
+}
+# the topmost popover open in this tree, or null
+function pp_top(root: UiNode) -> UiNode {
+  let all = new []UiNode
+  pp_find(root, all)
+  if len(all) == 0 { return null }
+  return all[len(all) - 1]
+}
+# the pointer against the popover: inside it is as usual; a press outside closes it and is spent
+function pp_pointer(top: UiNode) -> bool {
+  let i = in_now
+  if not (i.down and not in_was_down) { return false }
+  if i.x >= top.x and i.y >= top.y and i.x < top.x + top.cw and i.y < top.y + top.ch { return false }
+  ui_fire(top, "close", Value.null())
+  return true
+}
+function pp_draw_top() -> void {
+  let list = pop_list
+  pop_list = new []UiNode
+  for i in 0 .. len(list) { fr_draw(list[i]) }
+}
diff --git a/packages/ludic.ui/render3d.ludic b/packages/ludic.ui/render3d.ludic
index 66ed3df5..9ecb198e 100644
--- a/packages/ludic.ui/render3d.ludic
+++ b/packages/ludic.ui/render3d.ludic
@@ -1,5 +1,5 @@
 # render3d.ludic - ludic.ui drawn with ludic.render3d's overlay. A program that draws with render3d
-# imports this and calls ui_render3d() once; its templates then draw in the overlay pass, sized in
+# imports this, and its templates draw in the overlay pass (ui_render3d() installs it again), sized in
 # design pixels of a 1080-line screen (ui_render3d_scale sets the player's own interface size).
 #   <img src="path/to/picture.png">      a texture, loaded once
 #   <img src="icon:tent">                 a cell of an atlas the program named with ui_atlas
@@ -12,7 +12,14 @@ var r3u_tex_ids: []int = new []int
 var r3u_atlas: []string = new []string
 var r3u_atlas_tex: []int = new []int
 var r3u_atlas_cols: []int = new []int
+var r3u_atlas_rows: []int = new []int
 var r3u_atlas_names: [][]string = new [][]string
+var r3u_installed: bool = r3u_install()
+# importing this file is enough: it is the renderer from the program's first frame
+function r3u_install() -> bool {
+  ui_render3d()
+  return true
+}
 export function ui_render3d() -> void {
   let b = new UiBackend
   b.rect = fn r3u_rect
@@ -30,11 +37,13 @@ export function ui_render3d() -> void {
 }
 # the player's interface size, 1.0 as designed
 export function ui_render3d_scale(s: float) -> void { r3u_user = s }
-# a grid atlas: `names` are its cells, row by row, `cols` to a row; <img src="prefix:name"> draws one
-export function ui_atlas(prefix: string, tex: int, cols: int, names: []string) -> void {
+# a grid atlas: `names` are its cells, row by row, `cols` across and `rows` down; <img
+# src="prefix:name"> draws one (by its name, or by its number: "item:12")
+export function ui_atlas(prefix: string, tex: int, cols: int, rows: int, names: []string) -> void {
   push(r3u_atlas, prefix)
   push(r3u_atlas_tex, tex)
   push(r3u_atlas_cols, cols)
+  push(r3u_atlas_rows, Math.max(rows, 1))
   push(r3u_atlas_names, names)
 }
 function r3u_now() -> float { return float(Time.now_us() / 1000) / 1000.0 }
diff --git a/packages/ludic.ui/render3d_image.ludic b/packages/ludic.ui/render3d_image.ludic
index e833f3e7..ee95a98a 100644
--- a/packages/ludic.ui/render3d_image.ludic
+++ b/packages/ludic.ui/render3d_image.ludic
@@ -37,17 +37,19 @@ function r3u_cell(k: int, name: string, x: float, y: float, w: float, h: float,
   for i in 0 .. len(names) {
     if names[i] == name { idx = i }
   }
+  if idx < 0 and len(name) > 0 and name[0] >= 48 and name[0] <= 57 { idx = int(el_num(name)) }
   if idx < 0 {
     ui_err(`{r3u_atlas[k]}:{name}: the atlas has no such picture`)
     return
   }
   let cols = r3u_atlas_cols[k]
+  let rows = r3u_atlas_rows[k]
   let cx = idx % cols
   let cy = idx / cols
   let u0 = float(cx) / float(cols)
-  let v0 = float(cy) / float(cols)
+  let v0 = float(cy) / float(rows)
   let s = Math.min(w, h)
-  ov_sub(r3u_atlas_tex[k], int(x + (w - s) / 2.0), int(y + (h - s) / 2.0), int(s), int(s), u0, v0, u0 + 1.0 / float(cols), v0 + 1.0 / float(cols), r3u_r(c), r3u_g(c), r3u_b(c), a)
+  ov_sub(r3u_atlas_tex[k], int(x + (w - s) / 2.0), int(y + (h - s) / 2.0), int(s), int(s), u0, v0, u0 + 1.0 / float(cols), v0 + 1.0 / float(rows), r3u_r(c), r3u_g(c), r3u_b(c), a)
 }
 # border-image: the texture's `slice`-pixel corners kept, the rest stretched, drawn `dst` wide
 function r3u_nine(src: string, slice: float, x: float, y: float, w: float, h: float, dst: float, c: int, a: float) -> void {
diff --git a/packages/ludic.ui/tooltip.ludic b/packages/ludic.ui/tooltip.ludic
new file mode 100644
index 00000000..9c24a466
--- /dev/null
+++ b/packages/ludic.ui/tooltip.ludic
@@ -0,0 +1,47 @@
+# tooltip.ludic - an element's title="..." shown beside the pointer once it has rested on the
+# element for half a second, in a box styled by .ui-tooltip (the default sheet's, or a theme's)
+var tt_key: string = ""
+var tt_since: float = 0.0
+var tt_text: string = ""
+var tt_x: float = 0.0
+var tt_y: float = 0.0
+function tt_track(scope: UiNode, x: float, y: float) -> void {
+  let n = tt_under(scope, x, y)
+  if n == null {
+    tt_key = ""
+    return
+  }
+  if n.key != tt_key {
+    tt_key = n.key
+    tt_since = an_now()
+  }
+  tt_text = ui_tr(ui_attr_text(n, "title"))
+  tt_x = x
+  tt_y = y
+}
+# the deepest element under the point that has a title
+function tt_under(n: UiNode, x: float, y: float) -> UiNode {
+  if x < n.x or y < n.y or x >= n.x + n.cw or y >= n.y + n.ch { return null }
+  var i = len(n.children) - 1
+  while i >= 0 {
+    let t = tt_under(n.children[i], x, y)
+    if t != null { return t }
+    i -= 1
+  }
+  if n.akeys != null and ui_attr_text(n, "title") != "" { return n }
+  return null
+}
+function tt_draw(root: UiNode) -> void {
+  if tt_key == "" or tt_text == "" or an_now() - tt_since < 0.5 { return }
+  let n = ct_part(root, "ui-tooltip", "")
+  n.tag = "div"
+  n.parent = root
+  n.children = new []UiNode
+  push(n.children, ct_part(root, "ui-tooltip-text", tt_text))
+  cs_tree(n)
+  ly_measure(n, ly_vp_w * 0.4, ui_px(16.0), root.rfg)
+  let x = Math.min(tt_x + ui_px(16.0), ly_vp_x + ly_vp_w - n.mw)
+  let y = Math.min(tt_y + ui_px(20.0), ly_vp_y + ly_vp_h - n.mh)
+  ly_place(n, x, y, n.mw, n.mh)
+  fr_draw(n)
+}
diff --git a/packages/ludic.ui/ua.ludic b/packages/ludic.ui/ua.ludic
index a70b4ca4..e00b4588 100644
--- a/packages/ludic.ui/ua.ludic
+++ b/packages/ludic.ui/ua.ludic
@@ -1,4 +1,4 @@
 # ua.ludic - what every element looks like before a program styles it, as a browser's own sheet
 # does: headings sized, buttons and controls usable and plain, a focus ring. A theme overrides any
 # of it, with the same selectors or with the variables it reads.
-const UA_LSS: string = "h1 { font-size: 32 } h2 { font-size: 26 } h3 { font-size: 22 } h4 { font-size: 19 } h5 { font-size: 16 } h6 { font-size: 14 } small { font-size: 13 } hr { height: 1; width: fill; background: #808080; margin: 4 0 } scroll { width: fill; height: fill } img { width: 24; height: 24 } button { align-items: center; justify-content: center; gap: 8; padding: 6 14; background: #3a3f46; border-radius: 4 } button:hover { background: #4a5058 } button:disabled { opacity: 0.4 } :focus-visible { outline: 2px solid #ffcc55; outline-offset: 2 } input, select { align-items: center; gap: 10; padding: 6 10 } .ui-label { flex-grow: 1 } .ui-track { width: 44; height: 22; padding: 3; background: #555a60; border-radius: 11 } .ui-knob { width: 16; height: 16; background: #eeeeee; border-radius: 8 } input:checked .ui-track { justify-content: end; background: #d9a54a } input[type=range] .ui-track { width: 200; height: 8; padding: 0; border-radius: 4 } .ui-fill { height: fill; background: #d9a54a; justify-content: end; align-items: center; border-radius: 4 } .ui-thumb { width: 14; height: 14; background: #eeeeee; border-radius: 7; margin-right: -7 } .ui-value { min-width: 40 } .ui-field { width: 200; padding: 4 8; background: #202428; border: 1px solid #555a60 } .ui-caret { width: 2; height: 1.2em; background: #eeeeee } .ui-prev, .ui-next { color: #aaaaaa }"
+const UA_LSS: string = "h1 { font-size: 32 } h2 { font-size: 26 } h3 { font-size: 22 } h4 { font-size: 19 } h5 { font-size: 16 } h6 { font-size: 14 } small { font-size: 13 } hr { height: 1; width: fill; background: #808080; margin: 4 0 } scroll { width: fill; height: fill } img { width: 24; height: 24 } button { align-items: center; justify-content: center; gap: 8; padding: 6 14; background: #3a3f46; border-radius: 4 } button:hover { background: #4a5058 } button:disabled { opacity: 0.4 } :focus-visible { outline: 2px solid #ffcc55; outline-offset: 2 } input, select { align-items: center; gap: 10; padding: 6 10 } .ui-label { flex-grow: 1 } .ui-track { width: 44; height: 22; padding: 3; background: #555a60; border-radius: 11 } .ui-knob { width: 16; height: 16; background: #eeeeee; border-radius: 8 } input:checked .ui-track { justify-content: end; background: #d9a54a } input[type=range] .ui-track { width: 200; height: 8; padding: 0; border-radius: 4 } .ui-fill { height: fill; background: #d9a54a; justify-content: end; align-items: center; border-radius: 4 } .ui-thumb { width: 14; height: 14; background: #eeeeee; border-radius: 7; margin-right: -7 } .ui-value { min-width: 40 } .ui-field { width: 200; padding: 4 8; background: #202428; border: 1px solid #555a60 } .ui-caret { width: 2; height: 1.2em; background: #eeeeee } .ui-prev, .ui-next { color: #aaaaaa } progress, meter { width: 160; height: 10; background: #202428; border-radius: 5 } progress .ui-fill, meter .ui-fill { justify-content: start; border-radius: 5 } [popover] { position: absolute; z-index: 900 } .ui-tooltip { position: fixed; padding: 6 10; background: #202428; border: 1px solid #555a60; font-size: 15; z-index: 1000 }"
diff --git a/selfhost/ludicc.seed.ll b/selfhost/ludicc.seed.ll
index 145fbd01..3c41ce39 100644
--- a/selfhost/ludicc.seed.ll
+++ b/selfhost/ludicc.seed.ll
@@ -12771,7 +12771,7 @@ declare void @hs_free(i32)
 @.str12493 = private unnamed_addr constant [2 x i8] c" \00"
 @.str12494 = private unnamed_addr constant [50 x i8] c" -Wl,/subsystem:windows -Wl,/entry:mainCRTStartup\00"
 @.str12495 = private unnamed_addr constant [3 x i8] c" \22\00"
-@.str12496 = private unnamed_addr constant [55 x i8] c"build/cfree/selfhost.ludic:17806: index out of range: \00"
+@.str12496 = private unnamed_addr constant [55 x i8] c"build/cfree/selfhost.ludic:17808: index out of range: \00"
 @.str12497 = private unnamed_addr constant [2 x i8] c"\22\00"
 @.str12498 = private unnamed_addr constant [5 x i8] c" -o \00"
 @.str12499 = private unnamed_addr constant [2 x i8] c"\22\00"
@@ -134235,6 +134235,8 @@ ifend89:
   br label %ifend86
 ifend86:
   store i32 0, ptr @g_g_parsing
+  call void @fn_check_duplicate_fns()
+  call void @fn_check_duplicate_decls()
   call void @fn_check_program()
   call void @fn_emit_program()
   %t230 = load i32, ptr %t3
diff --git a/selfhost/ludicc.win.seed.ll b/selfhost/ludicc.win.seed.ll
index 861c5e36..dd189847 100644
--- a/selfhost/ludicc.win.seed.ll
+++ b/selfhost/ludicc.win.seed.ll
@@ -13088,7 +13088,7 @@ entry:
 @.str12493 = private unnamed_addr constant [2 x i8] c" \00"
 @.str12494 = private unnamed_addr constant [50 x i8] c" -Wl,/subsystem:windows -Wl,/entry:mainCRTStartup\00"
 @.str12495 = private unnamed_addr constant [3 x i8] c" \22\00"
-@.str12496 = private unnamed_addr constant [55 x i8] c"build/cfree/selfhost.ludic:17806: index out of range: \00"
+@.str12496 = private unnamed_addr constant [55 x i8] c"build/cfree/selfhost.ludic:17808: index out of range: \00"
 @.str12497 = private unnamed_addr constant [2 x i8] c"\22\00"
 @.str12498 = private unnamed_addr constant [5 x i8] c" -o \00"
 @.str12499 = private unnamed_addr constant [2 x i8] c"\22\00"
@@ -134538,6 +134538,8 @@ ifend89:
   br label %ifend86
 ifend86:
   store i32 0, ptr @g_g_parsing
+  call void @fn_check_duplicate_fns()
+  call void @fn_check_duplicate_decls()
   call void @fn_check_program()
   call void @fn_emit_program()
   %t230 = load i32, ptr %t3
diff --git a/selfhost/main.ludic b/selfhost/main.ludic
index cdb5ae1e..6fac1896 100644
--- a/selfhost/main.ludic
+++ b/selfhost/main.ludic
@@ -203,6 +203,8 @@ entry {
   else { g_windowed = has_target and has_systems() }
 
   g_parsing = false                               # lowering errors now locate by statement, not token
+  check_duplicate_fns()                           # two declarations of one name: the cause, before its symptoms
+  check_duplicate_decls()
   check_program()                                 # L4: the types agree before anything is emitted
   emit_program()
 
diff --git a/tools/ludic-cli/test.ludic b/tools/ludic-cli/test.ludic
index 4aaf3490..3b6b1cad 100644
--- a/tools/ludic-cli/test.ludic
+++ b/tools/ludic-cli/test.ludic
@@ -759,6 +759,7 @@ function cmd_dev_test() -> int {
   reject_case("rejected/component_no_template", "there is no Lonely.xml beside it", "a component needs its template beside it")
   controller_case("library/ui_controls", "", "1 false 7 2 Adalove 70 1 false 8 2 Adalove 70; scrolled 40", "ui_controls.ludic (L11: focus and keys, the built-in controls, a range dragged, a box scrolled)")
   controller_case("library/ui_anim", "", "0 100 100 | 49 50 100 | 100 100 61", "ui_anim.ludic (L11: @keyframes and animation, looping and alternating, and a transition)")
+  controller_case("library/ui_popover", "", "drop false | drop true | drop false | drop false | fill 60 of 200", "ui_popover.ludic (L11: a popover keeps the keys and closes on a press outside or Esc; progress fills)")
   reject_case("rejected/view_untyped", "view Sums: say what type total is", "a view field that is not a bare global says its type")
   reject_case("rejected/view_without_ui", "a view is shown by ludic.ui", "a view needs ludic.ui to show it")