feat(window): restore the title-bar, hide-button, and 24-hour-clock toggles

Re-wires four 1.5.6 settings that survived the v1.6.0 rewrite as dormant config
fields but lost their UI + consumers:
- ShowTitleBar / ShowPopOutTitleBar: gate ImGuiWindowFlags.NoTitleBar on the main
  window (ResolveFlags) and pop-out windows (new PreDraw). Inverted logic matches
  1.5.6 (flag set only when the toggle is off).
- ShowHideButton: gate the input-bar hide button on the toggle.
- Use24HourClock: add the toggle (MessageList already consumes the field).
New 'Window style' section in WindowTab; Use24HourClock in ChatTab display modes.
MainWindowFlagsStep extended with the NoTitleBar fresh-base contract.

HellionChat/SelfTests/MainWindowFlagsStep.cs

@@ -34,7 +34,11 @@ internal sealed class MainWindowFlagsStep : ISelfTestStep
         // value for the live config. No state mutation needed.
         var savedFlags = window.Flags;
         window.PreDraw();
-        var expected = MainWindow.ResolveFlags(Plugin.Config.CanMove, Plugin.Config.CanResize);
+        var expected = MainWindow.ResolveFlags(
+            Plugin.Config.CanMove,
+            Plugin.Config.CanResize,
+            Plugin.Config.ShowTitleBar
+        );
         if (window.Flags != expected)
         {
             ImGui.Text($"PreDraw set Flags {window.Flags}, expected ResolveFlags = {expected}");
@@ -43,7 +47,7 @@ internal sealed class MainWindowFlagsStep : ISelfTestStep
         }
 
         // Fresh-base contract: locked window carries NoMove|NoResize ...
-        var locked = MainWindow.ResolveFlags(false, false);
+        var locked = MainWindow.ResolveFlags(false, false, true);
         if (
             !locked.HasFlag(ImGuiWindowFlags.NoMove)
             || !locked.HasFlag(ImGuiWindowFlags.NoResize)
@@ -51,17 +55,35 @@ internal sealed class MainWindowFlagsStep : ISelfTestStep
         )
         {
             ImGui.Text(
-                $"ResolveFlags(false,false) = {locked}, missing NoMove/NoResize/NoScrollbar"
+                $"ResolveFlags(false,false,true) = {locked}, missing NoMove/NoResize/NoScrollbar"
             );
             window.Flags = savedFlags;
             return SelfTestStepResult.Fail;
         }
 
         // ... and re-enabling both CLEARS NoMove|NoResize (no accumulation).
-        var free = MainWindow.ResolveFlags(true, true);
+        var free = MainWindow.ResolveFlags(true, true, true);
         if (free.HasFlag(ImGuiWindowFlags.NoMove) || free.HasFlag(ImGuiWindowFlags.NoResize))
         {
-            ImGui.Text($"ResolveFlags(true,true) = {free}, NoMove/NoResize stuck after re-enable");
+            ImGui.Text(
+                $"ResolveFlags(true,true,true) = {free}, NoMove/NoResize stuck after re-enable"
+            );
+            window.Flags = savedFlags;
+            return SelfTestStepResult.Fail;
+        }
+
+        // P7 title-bar contract: ShowTitleBar=false adds NoTitleBar from the
+        // fresh base, true clears it (same no-accumulation guarantee).
+        var barHidden = MainWindow.ResolveFlags(true, true, false);
+        var barShown = MainWindow.ResolveFlags(true, true, true);
+        if (
+            !barHidden.HasFlag(ImGuiWindowFlags.NoTitleBar)
+            || barShown.HasFlag(ImGuiWindowFlags.NoTitleBar)
+        )
+        {
+            ImGui.Text(
+                $"NoTitleBar wiring wrong: hidden={barHidden} (want NoTitleBar), shown={barShown} (want none)"
+            );
             window.Flags = savedFlags;
             return SelfTestStepResult.Fail;
         }

HellionChat/Ui/Components/InputBar.cs

@@ -540,15 +540,21 @@ internal sealed class InputBar
                     ImGui.SetTooltip("Settings");
             }
 
-            ImGui.SameLine();
-            var hidden = Plugin.Config.HideChat;
-            var visIcon = hidden ? FontAwesomeIcon.EyeSlash : FontAwesomeIcon.Eye;
-            if (ImGui.Button(visIcon.ToIconString()))
-                Plugin.Config.HideChat = !hidden;
-            if (ImGui.IsItemHovered())
+            // Hide button gated on ShowHideButton (1.5.6 parity). It is the last
+            // button in the row, so skipping it (with its leading SameLine) leaves
+            // no dangling SameLine. Shared by main + pop-out InputBars.
+            if (Plugin.Config.ShowHideButton)
             {
-                using (ImRaii.DefaultFont())
-                    ImGui.SetTooltip(hidden ? "Unhide chat" : "Hide chat");
+                ImGui.SameLine();
+                var hidden = Plugin.Config.HideChat;
+                var visIcon = hidden ? FontAwesomeIcon.EyeSlash : FontAwesomeIcon.Eye;
+                if (ImGui.Button(visIcon.ToIconString()))
+                    Plugin.Config.HideChat = !hidden;
+                if (ImGui.IsItemHovered())
+                {
+                    using (ImRaii.DefaultFont())
+                        ImGui.SetTooltip(hidden ? "Unhide chat" : "Hide chat");
+                }
             }
         }
     }

HellionChat/Ui/Components/Settings/Tabs/ChatTab.cs

@@ -38,6 +38,11 @@ internal sealed class ChatTab
                 () => Plugin.Config.HideSameTimestamps,
                 v => Plugin.Config.HideSameTimestamps = v
             );
+            DrawToggle(
+                "24-hour clock",
+                () => Plugin.Config.Use24HourClock,
+                v => Plugin.Config.Use24HourClock = v
+            );
             DrawWorldSuffixCombo();
             DrawNameFormCombo();
         }

HellionChat/Ui/Components/Settings/Tabs/WindowTab.cs

@@ -28,6 +28,25 @@ internal sealed class WindowTab
             }
         }
 
+        if (ImGui.CollapsingHeader("Window style", ImGuiTreeNodeFlags.DefaultOpen))
+        {
+            DrawToggle(
+                "Show title bar",
+                () => Plugin.Config.ShowTitleBar,
+                v => Plugin.Config.ShowTitleBar = v
+            );
+            DrawToggle(
+                "Show title bar for pop-outs",
+                () => Plugin.Config.ShowPopOutTitleBar,
+                v => Plugin.Config.ShowPopOutTitleBar = v
+            );
+            DrawToggle(
+                "Show hide button",
+                () => Plugin.Config.ShowHideButton,
+                v => Plugin.Config.ShowHideButton = v
+            );
+        }
+
         if (ImGui.CollapsingHeader("Opacity", ImGuiTreeNodeFlags.DefaultOpen))
         {
             DrawSlider(

HellionChat/Ui/Windows/ChannelPopoutWindow.cs

@@ -75,6 +75,17 @@ internal sealed class ChannelPopoutWindow : Window
         IsOpen = false;
     }
 
+    public override void PreDraw()
+    {
+        // Gate the native title bar on the user toggle (1.5.6 parity). DrawHeader
+        // carries the close button in-body regardless, so hiding the title bar
+        // never strands the pop-out. Reset from a fresh base each frame so
+        // toggling the bar back on clears NoTitleBar.
+        Flags = Plugin.Config.ShowPopOutTitleBar
+            ? ImGuiWindowFlags.None
+            : ImGuiWindowFlags.NoTitleBar;
+    }
+
     public override void Draw()
     {
         if (Bound is null)

HellionChat/Ui/Windows/MainWindow.cs

@@ -77,19 +77,21 @@ internal sealed class MainWindow : Window
     internal float ResolveBgAlpha(bool isFocused) =>
         isFocused ? Plugin.Config.WindowOpacity : Plugin.Config.WindowOpacityInactive;
 
-    // B1-2: rebuild flags from a fresh base every frame so toggling CanMove/
-    // CanResize back on actually CLEARS NoMove/NoResize (not accumulating).
-    // Move/resize toggle logic as 1.5.6 (ChatLogWindow.PreOpenCheck
-    // 1d3b429:703-707); base flags = today's MainWindow set (NoScrollbar|
-    // NoScrollWithMouse — the message list owns its own scroll; 1.5.6's
-    // NoFocusOnAppearing/NoTitleBar are deliberately not restored).
-    internal static ImGuiWindowFlags ResolveFlags(bool canMove, bool canResize)
+    // B1-2 / P7: rebuild flags from a fresh base every frame so toggling
+    // CanMove/CanResize/ShowTitleBar back on actually CLEARS NoMove/NoResize/
+    // NoTitleBar (not accumulating). Move/resize/title-bar logic as 1.5.6
+    // (ChatLogWindow.PreOpenCheck 1d3b429:703-710); base flags = today's
+    // MainWindow set (NoScrollbar|NoScrollWithMouse — the message list owns its
+    // own scroll; 1.5.6's NoFocusOnAppearing is deliberately not restored).
+    internal static ImGuiWindowFlags ResolveFlags(bool canMove, bool canResize, bool showTitleBar)
     {
         var flags = ImGuiWindowFlags.NoScrollbar | ImGuiWindowFlags.NoScrollWithMouse;
         if (!canMove)
             flags |= ImGuiWindowFlags.NoMove;
         if (!canResize)
             flags |= ImGuiWindowFlags.NoResize;
+        if (!showTitleBar)
+            flags |= ImGuiWindowFlags.NoTitleBar;
         return flags;
     }
 
@@ -114,7 +116,11 @@ internal sealed class MainWindow : Window
                 BgAlpha = null;
         }
 
-        Flags = ResolveFlags(Plugin.Config.CanMove, Plugin.Config.CanResize);
+        Flags = ResolveFlags(
+            Plugin.Config.CanMove,
+            Plugin.Config.CanResize,
+            Plugin.Config.ShowTitleBar
+        );
     }
 
     public Tab? ActiveTab => _activeTab;