Fixes #5211. FlagSelector ENTER should not toggle, just accept.

Terminal.Gui/Views/Selectors/FlagSelector.cs

@@ -7,7 +7,7 @@ namespace Terminal.Gui.Views;
 //  Item HotKey - Focus item. Activate (Toggle) item. Do NOT Accept.
 // Focused:
 //  Space key - Activate (Toggle) focused item. Do NOT Accept.
-//  Enter key - Activate (Toggle) and Accept the focused item.
+//  Enter key - Accept. Do NOT Toggle.
 //  HotKey - No-op.
 //  Item HotKey - Focus item, Activate (Toggle), and do NOT Accept.
 
@@ -60,6 +60,11 @@ public FlagSelector ()
     /// </summary>
     protected override bool ConsumeDispatch => true;
 
+    /// <summary>
+    ///     FlagSelector does not toggle on Enter — Enter only accepts.
+    /// </summary>
+    protected override bool ActivateOnAccept => false;
+
     // Set by OnHandlingHotKey to suppress the Activate that DefaultHotKeyHandler
     // fires after RaiseHandlingHotKey. Checked and cleared in GetDispatchTarget.
     private bool _suppressHotKeyActivate;

Terminal.Gui/Views/Selectors/SelectorBase.cs

@@ -159,6 +159,13 @@ public SelectorStyles Styles
         }
     }
 
+    /// <summary>
+    ///     Gets whether the Accept command (Enter key) should also invoke Activate (toggle/select) before accepting.
+    ///     The default is <see langword="true"/> (OptionSelector behavior). Override to return <see langword="false"/>
+    ///     to accept without activating (FlagSelector behavior).
+    /// </summary>
+    protected virtual bool ActivateOnAccept => true;
+
     /// <inheritdoc/>
     protected override bool OnAccepting (CommandEventArgs args)
     {
@@ -167,7 +174,7 @@ protected override bool OnAccepting (CommandEventArgs args)
             return true;
         }
 
-        // Per spec: Enter key should Activate AND Accept for both OptionSelector and FlagSelector.
+        // Per spec: Enter key should Activate AND Accept for OptionSelector.
         // Enter only triggers Command.Accept (View's default key binding), so invoke Activate here
         // before continuing with Accept processing. Also handle direct programmatic Accept invocations
         // (Binding is null) by activating the currently focused checkbox.
@@ -178,7 +185,7 @@ protected override bool OnAccepting (CommandEventArgs args)
 
         bool directAccept = args.Context?.Binding is null && Focused is CheckBox;
 
-        if (!enterFromCheckBox && !directAccept)
+        if ((!enterFromCheckBox && !directAccept) || !ActivateOnAccept)
         {
             return args.Context?.Binding switch
             {

Tests/UnitTestsParallelizable/Views/FlagSelectorTests.cs

@@ -151,6 +151,36 @@ public void FlagSelector_Command_HotKey_WhenFocused_Does_Not_Change_Value ()
         Assert.Equal (valueBefore, flagSelector.Value);
     }
 
+    // Copilot - Sonnet 4
+    // Per issue: Enter should just accept, not toggle, in FlagSelector
+    [Fact]
+    public void FlagSelector_Enter_Does_Not_Toggle_Value ()
+    {
+        using FlagSelector<SelectorStyles> flagSelector = new ();
+
+        CheckBox firstCheckBox = flagSelector.SubViews.OfType<CheckBox> ().ElementAt (0);
+        flagSelector.SetFocus ();
+        Assert.True (flagSelector.HasFocus);
+
+        SelectorStyles? valueBefore = flagSelector.Value;
+
+        int selectorValueChanged = 0;
+        flagSelector.ValueChanged += (_, _) => selectorValueChanged++;
+
+        int acceptingFired = 0;
+        flagSelector.Accepting += (_, _) => acceptingFired++;
+
+        // Press Enter on the focused checkbox
+        firstCheckBox.NewKeyDownEvent (Key.Enter);
+
+        // Value should NOT change (Enter does not toggle in FlagSelector)
+        Assert.Equal (0, selectorValueChanged);
+        Assert.Equal (valueBefore, flagSelector.Value);
+
+        // But Accepting should fire
+        Assert.Equal (1, acceptingFired);
+    }
+
     // Tests for FlagSelector<TEnum>
     [Fact]
     public void GenericInitialization_ShouldSetDefaults ()