re: placement X/Y are SIGNED, the tail word is time, and the resting pose is max-dwell

Dumping the remaining Arsenal components turned up placements reading as
4294966780 and 4294966856 -- negative as i32 (-516, -440). X and Y are signed;
off-screen animation starts are negative, and read as unsigned a reimplementation
would draw them four billion pixels off.

The raw region then showed the rest of it. The trailing word is a TIME, and a
group is an in -> hold -> out animation: prselect_win1 runs
t=4:-516 -> 6:-71 -> 7:81 -> 8:127 -> 23:134 -> 24:134 -> 25:127 -> 27:81 ->
31:-71 -> 1:-516. So NEITHER the first nor the last keyframe is where the element
sits -- both are off-screen. The resting position is the max-dwell keyframe,
(127,155)..(134,155) here, which is where the weapon-list panel actually appears.

This corrects my own note from earlier today, which reported "final=" positions.
Static elements were unaffected (the pause menu's buttons have identical
keyframes) but animated ones were misread. screen_layout.rs now reports the
max-dwell pose plus the full timeline, and both captures are regenerated.

Also seen while dumping: kind 0x2, and a .sbo child (scrollbar) parented to the
list window.

Co-Authored-By: Claude Opus 5 (1M context) <noreply@anthropic.com>

docs/re/structures/ui-rat-layout.md

@@ -202,17 +202,33 @@ recording them because a static-only reading would have shipped them:
   ```
   group header:  u32 element index      (0,1,2… — the correspondence is stated, not inferred)
                  u32 keyframe count
-  then `count` keyframes, 40 bytes apart, each holding the familiar block:
+  then `count` keyframes, 40 bytes apart, each holding:
                  u32 scale X = 100      u32 scale Y = 100
                  u32 tint    = 0xffffffff
-                 u32 X                  u32 Y            (+ a trailing time field)
+                 i32 X                  i32 Y            ← SIGNED
+                 u32 time               u32 flags/terminator
   ```
 
+  **Three things here are easy to get wrong, and were:**
+
+  - **X and Y are signed.** Off-screen animation starts are negative — the Arsenal's
+    weapon-list window begins at **X = −516**. Read as unsigned it is 4 294 966 780,
+    which a naïve implementation would happily draw four billion pixels to the right.
+  - **The trailing word is a time**, and a group is an **in → hold → out**
+    animation. `prselect_win1` runs `t=4:−516 → 6:−71 → 7:81 → 8:127 → 23:134 →
+    24:134 → 25:127 → 27:81 → 31:−71 → 1:−516`.
+  - **So neither the first nor the last keyframe is where the element sits.** Both
+    are off-screen for an animated element. The resting position is the
+    **max-dwell** keyframe — the one with the longest gap to the next time — which
+    for that window is **(127,155)…(134,155)**, matching where the list panel
+    actually appears. `screen_layout.rs` reports that, not `final`.
+
   For the tutorial pause bundle this yields 11 groups for 11 elements, and every
   group's header index and count match the blocks actually present. The values are
   self-evidently right: the three menu buttons sit at X=546, **70 px apart**
-  (288 / 358 / 428), the title at (540,119), the message at (451,545), and the
-  `eff*` sprites carry multi-position fly-ins.
+  (288 / 358 / 428) — static, every keyframe identical, which is why their reading
+  was unaffected by the first/last mistake above — the title at (540,119), the
+  message at (451,545), and the `eff*` sprites carry multi-position fly-ins.
 
   **Cross-checked against the records themselves:** `pgp_ttrl_btn10.rat` places its
   sprite at **(546,288)** — identical to its inline group. So the inline region is