fix(ui): move scroll-to-bottom button into the chat header toolbar

Drop the three-attempt floating overlay entirely. The button now lives in
the chat header toolbar (DrawScrollToBottomToolbarButton), visible only when
the user is scrolled above the live end. Toolbar layout: honorific slot,
scroll button, pop-out button flush-right -- pop-out position unchanged.

HellionChat/Ui/ChatLogWindow.cs

@@ -1544,20 +1544,8 @@ public sealed class ChatLogWindow : Window
         CurrentHideState = HideState.User;
     }
 
-    internal void DrawMessageLog(
+    internal void DrawMessageLog(Tab tab, PayloadHandler handler, float childHeight, bool switchedTab)
-        Tab tab,
-        PayloadHandler handler,
-        float childHeight,
-        bool switchedTab,
-        string ownerId = "main"
-    )
     {
-        // Capture these before entering the child so we can position the overlay
-        // button in the parent window's coordinate space afterward. Inside the
-        // child the same queries would return child-local values.
-        var childScreenPos = ImGui.GetCursorScreenPos();
-        var childWidth     = ImGui.GetContentRegionAvail().X;
-
         using (var child = ImRaii.Child("##chat2-messages", new Vector2(-1, childHeight)))
         {
             if (child.Success)
@@ -1567,8 +1555,9 @@ public sealed class ChatLogWindow : Window
                 else
                     DrawLogNormalStyle(tab, handler, switchedTab);
 
-                // Cache scroll state while we are still inside the child so
+                // Cached for the header toolbar's scroll-to-bottom button, which is
-                // GetScrollMaxY / GetScrollY refer to the child's scroll context.
+                // drawn one frame later. GetScrollMaxY / GetScrollY here refer to
+                // the child's scroll context.
                 _childScrolledUp = ImGui.GetScrollMaxY() - ImGui.GetScrollY() > 1f;
             }
             else
@@ -1576,13 +1565,6 @@ public sealed class ChatLogWindow : Window
                 _childScrolledUp = false;
             }
         }
-
-        // Draw the overlay button in the parent window, outside the child.
-        // This prevents the button from inflating ScrollMaxY inside the child
-        // (which caused it to drift) and avoids the scrollbar's inner clip rect
-        // (which caused it to be cut off on the right edge).
-        if (_childScrolledUp)
-            DrawScrollToBottomButtonOverlay(childScreenPos, childWidth, childHeight, ownerId);
     }
 
     private void DrawLogNormalStyle(Tab tab, PayloadHandler handler, bool switchedTab)
@@ -1632,61 +1614,6 @@ public sealed class ChatLogWindow : Window
 
     }
 
-    // UI-5: floating jump-to-latest button.
-    //
-    // Why a standalone overlay window rather than drawing in the parent?
-    // When this button was drawn in the parent window after the ##chat2-messages
-    // child closed, ImGui's hit-test still resolved g.HoveredWindow to the child
-    // (the child occupies the same screen rect). ItemHoverable then rejected the
-    // button submitted in the parent, so it was visible but never clickable.
-    //
-    // A top-level Begin/End window is a sibling in the window list, not nested
-    // under the child, so it wins the hit-test for its own rect and the button
-    // inside it is fully clickable.
-    //
-    // The ownerId parameter makes the window name unique per calling context so
-    // the main window and each pop-out don't share a single ImGui window entry.
-    private void DrawScrollToBottomButtonOverlay(
-        Vector2 childScreenPos,
-        float childWidth,
-        float childHeight,
-        string ownerId)
-    {
-        var size           = ImGui.GetFrameHeight();
-        var pad            = 8f * ImGuiHelpers.GlobalScale;
-        var scrollbarWidth = ImGui.GetStyle().ScrollbarSize;
-
-        // Position confirmed correct in-game: bottom-right of the chat child,
-        // inset by pad, and pulled left of the vertical scrollbar.
-        var btnPos = new Vector2(
-            childScreenPos.X + childWidth  - scrollbarWidth - size - pad,
-            childScreenPos.Y + childHeight -                  size - pad);
-
-        ImGui.SetNextWindowPos(btnPos, ImGuiCond.Always);
-        ImGui.SetNextWindowSize(new Vector2(size, size), ImGuiCond.Always);
-
-        const ImGuiWindowFlags overlayFlags =
-            ImGuiWindowFlags.NoTitleBar
-            | ImGuiWindowFlags.NoResize
-            | ImGuiWindowFlags.NoMove
-            | ImGuiWindowFlags.NoScrollbar
-            | ImGuiWindowFlags.NoScrollWithMouse
-            | ImGuiWindowFlags.NoSavedSettings
-            | ImGuiWindowFlags.NoFocusOnAppearing
-            | ImGuiWindowFlags.NoBackground;
-
-        // End() must be called unconditionally after Begin() — ImGui rule.
-        if (ImGui.Begin($"##scroll-to-bottom-overlay-{ownerId}", overlayFlags))
-        {
-            if (ImGuiUtil.IconButton(
-                    FontAwesomeIcon.ArrowDown,
-                    tooltip: HellionStrings.ChatLog_ScrollToBottom_Tooltip))
-                _scrollToBottomRequested = true;
-        }
-
-        ImGui.End();
-    }
-
     private void DrawMessages(
         Tab tab,
         PayloadHandler handler,
@@ -2390,14 +2317,42 @@ public sealed class ChatLogWindow : Window
         Plugin.WantedTab = null;
     }
 
-    // DrawChatHeaderToolbar: renders the pop-out button for the active tab.
+    // DrawChatHeaderToolbar: renders the honorific title slot, the optional
-    // v1.3.0 also renders the optional Honorific title slot left of it.
+    // scroll-to-bottom button, and the pop-out button for the active tab.
+    // v1.3.0 added the title slot; v1.5.5 added the scroll-to-bottom button.
     private void DrawChatHeaderToolbar(Tab tab)
     {
         DrawHonorificTitleSlot();
+        DrawScrollToBottomToolbarButton();
         DrawPopOutButton(tab);
     }
 
+    // Draws an arrow-down button in the toolbar when the user has scrolled up
+    // from the live end of the chat log. Clicking it requests a snap to bottom.
+    //
+    // _childScrolledUp is set at the end of DrawMessageLog, which runs AFTER
+    // DrawChatHeaderToolbar in the same frame. So this button always reflects the
+    // previous frame's scroll state, a one-frame lag that is imperceptible in use.
+    //
+    // Both this button and DrawPopOutButton use SetCursorPosX with absolute
+    // positioning (cursorX + GetContentRegionAvail().X - N * iconWidth). Because
+    // each call computes its own target X from the right edge, they are independent
+    // of each other and of what the cursor position happens to be at call time.
+    // The pop-out button lands at rightEdge - iconWidth regardless of call order.
+    private void DrawScrollToBottomToolbarButton()
+    {
+        if (!_childScrolledUp)
+            return;
+
+        var avail = ImGui.GetContentRegionAvail().X;
+        var iconWidth = ImGui.GetFrameHeight();
+        var spacing = ImGui.GetStyle().ItemSpacing.X;
+        ImGui.SetCursorPosX(ImGui.GetCursorPosX() + avail - 2 * iconWidth - spacing);
+
+        if (ImGuiUtil.IconButton(FontAwesomeIcon.ArrowDown, tooltip: HellionStrings.ChatLog_ScrollToBottom_Tooltip))
+            _scrollToBottomRequested = true;
+    }
+
     private void DrawPopOutButton(Tab tab)
     {
         var avail = ImGui.GetContentRegionAvail().X;

HellionChat/Ui/Popout.cs

@@ -118,7 +118,7 @@ internal class Popout : Window
 
         var handler = ChatLogWindow.HandlerLender.Borrow();
         var logHeight = ImGui.GetContentRegionAvail().Y - inputBarHeight - hintBannerHeight;
-        ChatLogWindow.DrawMessageLog(Tab, handler, logHeight, false, Tab.Identifier.ToString());
+        ChatLogWindow.DrawMessageLog(Tab, handler, logHeight, false);
 
         if (inputEnabled && InputBar != null)
         {