feat(style): let a setting row render disabled

Six settings across the window only apply while another one is on. Today they
sit at full contrast and simply do nothing when clicked.

BeginDisabled cannot carry this: it pushes an alpha that ImGui applies inside
its own widgets, and every part of a setting row that a user reads -- label,
description, separator, hover fill -- is draw-list output that never sees it.
So the row fades itself, drops its click, and stops tracking hover.

The flag is passed through to the control callback as well. A draw-list control
handed into the row has exactly the same problem and no other way to learn about
it.

Note the parameter sits before styleOverride, so the one existing positional
call site had to name its argument.

HellionChat/Ui/Windows/WidgetGalleryWindow.cs

@@ -48,6 +48,7 @@ internal sealed class WidgetGalleryWindow : Window
         DrawSectionHeaderSection(c);
         DrawRowSection(c);
         DrawToggleSection(c);
+        DrawSegmentedSection(c);
         DrawSettingRowSection(c);
         DrawBadgeSection(c);
         DrawPillSection(c);
@@ -250,9 +251,84 @@ internal sealed class WidgetGalleryWindow : Window
             null,
             colors,
             _ => ImGui.SliderInt("##gallery-sr-d", ref _badgeCount, 0, 150),
-            new SettingRowStyle { DrawSeparator = false, PreferredControlWidth = 90f }
+            styleOverride: new SettingRowStyle
+            {
+                DrawSeparator = false,
+                PreferredControlWidth = 90f,
+            }
         );
 
+        // Disabled: the label fades, the row stops lighting up, and the click
+        // does not reach the setting.
+        using (ImRaii.Disabled())
+        {
+            SettingRow.Draw(
+                ImGui.GetID("gallery.settingrow.disabled"),
+                "Disabled row",
+                "Neither the row nor its control may respond.",
+                colors,
+                _ => ImGui.SliderInt("##gallery-sr-e", ref _badgeCount, 0, 150),
+                disabled: true
+            );
+        }
+
+        ImGui.Spacing();
+    }
+
+    // Segment labels are held rather than built per frame: a collection
+    // expression in the draw call would allocate a fresh array every frame.
+    private static readonly string[] SegmentLabelsTwo = ["Sidebar", "Top tabs"];
+    private static readonly string[] SegmentLabelsThree = ["Off", "Compact", "Full"];
+    private int _segmentTwo;
+    private int _segmentThree = 1;
+
+    private void DrawSegmentedSection(ThemeColors c)
+    {
+        var colors = new SegmentedControlColors
+        {
+            TrackAbgr = _palette.Abgr(Token.SurfaceBase, c),
+            SelectedAbgr = _palette.Abgr(Token.AccentPrimary, c),
+            HoverAbgr = _palette.Abgr(Token.SurfaceHover, c),
+            LabelAbgr = _palette.Abgr(Token.TextMuted, c),
+            SelectedLabelAbgr = _palette.Abgr(Token.Text, c),
+            BorderAbgr = _palette.Abgr(Token.Border, c),
+        };
+
+        var width = MathF.Min(260f * Metrics.Scale, ImGui.GetContentRegionAvail().X);
+
+        _segmentTwo = SegmentedControl.Draw(
+            ImGui.GetID("gallery.segmented.two"),
+            ImGui.GetCursorScreenPos(),
+            width,
+            SegmentLabelsTwo,
+            _segmentTwo,
+            colors
+        );
+        ImGui.Dummy(SegmentedControl.CalcSize(width));
+
+        _segmentThree = SegmentedControl.Draw(
+            ImGui.GetID("gallery.segmented.three"),
+            ImGui.GetCursorScreenPos(),
+            width,
+            SegmentLabelsThree,
+            _segmentThree,
+            colors
+        );
+        ImGui.Dummy(SegmentedControl.CalcSize(width));
+
+        // Odd width over three segments: the edges must stay flush with no seam
+        // and no overhang on the right.
+        SegmentedControl.Draw(
+            ImGui.GetID("gallery.segmented.odd"),
+            ImGui.GetCursorScreenPos(),
+            201f,
+            SegmentLabelsThree,
+            0,
+            colors,
+            disabled: true
+        );
+        ImGui.Dummy(SegmentedControl.CalcSize(201f));
+
         ImGui.Spacing();
     }