Add support for "focus follows mouse" mode (#8965)

## PR Checklist
* [x] Closes #6459
* [x] CLA signed.
* [ ] Tests added/passed
* [x] Documentation updated here: MicrosoftDocs/terminal#248
* [x] Schema updated.
* [x] I've discussed this with core contributors already.

doc/cascadia/profiles.schema.json

@@ -635,6 +635,11 @@
           "description": "When set to true, a selection is immediately copied to your clipboard upon creation. When set to false, the selection persists and awaits further action.",
           "type": "boolean"
         },
+        "focusFollowMouse": {
+          "default": false,
+          "description": "When set to true, the terminal will focus the pane on mouse hover.",
+          "type": "boolean"
+        },
         "copyFormatting": {
           "default": true,
           "description": "When set to `true`, the color and font formatting of selected text is also copied to your clipboard. When set to `false`, only plain text is copied to your clipboard. An array of specific formats can also be used. Supported array values include `html` and `rtf`. Plain text is always copied.",

src/cascadia/TerminalApp/TerminalSettings.cpp

@@ -208,6 +208,7 @@ namespace winrt::TerminalApp::implementation
 
         _WordDelimiters = globalSettings.WordDelimiters();
         _CopyOnSelect = globalSettings.CopyOnSelect();
+        _FocusFollowMouse = globalSettings.FocusFollowMouse();
         _ForceFullRepaintRendering = globalSettings.ForceFullRepaintRendering();
         _SoftwareRendering = globalSettings.SoftwareRendering();
         _ForceVTInput = globalSettings.ForceVTInput();

src/cascadia/TerminalApp/TerminalSettings.h

@@ -64,6 +64,7 @@ namespace winrt::TerminalApp::implementation
         GETSET_SETTING(uint32_t, CursorHeight, DEFAULT_CURSOR_HEIGHT);
         GETSET_SETTING(hstring, WordDelimiters, DEFAULT_WORD_DELIMITERS);
         GETSET_SETTING(bool, CopyOnSelect, false);
+        GETSET_SETTING(bool, FocusFollowMouse, false);
 
         GETSET_SETTING(Windows::Foundation::IReference<uint32_t>, TabColor, nullptr);
 

src/cascadia/TerminalControl/IControlSettings.idl

@@ -39,6 +39,7 @@ namespace Microsoft.Terminal.TerminalControl
         Microsoft.Terminal.TerminalControl.IKeyBindings KeyBindings;
 
         Boolean CopyOnSelect;
+        Boolean FocusFollowMouse;
 
         String Commandline;
         String StartingDirectory;

src/cascadia/TerminalControl/TermControl.cpp

@@ -1362,6 +1362,11 @@ namespace winrt::Microsoft::Terminal::TerminalControl::implementation
         const auto cursorPosition = point.Position();
         const auto terminalPosition = _GetTerminalPosition(cursorPosition);
 
+        if (!_focused && _settings.FocusFollowMouse())
+        {
+            Focus(FocusState::Pointer);
+        }
+
         if (ptr.PointerDeviceType() == Windows::Devices::Input::PointerDeviceType::Mouse || ptr.PointerDeviceType() == Windows::Devices::Input::PointerDeviceType::Pen)
         {
             if (_focused && _CanSendVTMouseInput())

src/cascadia/TerminalSettingsEditor/Interaction.xaml

@@ -54,6 +54,11 @@ the MIT License. See LICENSE in the project root for license information. -->
                                    ItemsSource="{x:Bind TabSwitcherModeList}"
                                    ItemTemplate="{StaticResource EnumRadioButtonTemplate}"/>
             </local:SettingContainer>
+
+            <!-- Focus Follow Mouse Mode-->
+            <local:SettingContainer x:Uid="Globals_FocusFollowMouse">
+                <ToggleSwitch IsOn="{x:Bind State.Globals.FocusFollowMouse, Mode=TwoWay}"/>
+            </local:SettingContainer>
         </StackPanel>
     </ScrollViewer>
 </Page>

src/cascadia/TerminalSettingsEditor/Resources/en-US/Resources.resw

@@ -825,4 +825,10 @@
     <value>a lower layer</value>
     <comment>This is the object of "SettingContainer_OverrideIntro".</comment>
   </data>
+  <data name="Globals_FocusFollowMouse.Header" xml:space="preserve">
+    <value>Enable Focus Follow Mouse mode</value>
+  </data>
+  <data name="Globals_FocusFollowMouse.HelpText" xml:space="preserve">
+    <value>When checked, the terminal will the focus pane on mouse hover.</value>
+  </data>
 </root>

src/cascadia/TerminalSettingsModel/GlobalAppSettings.cpp

@@ -41,6 +41,7 @@ static constexpr std::string_view LegacyUseTabSwitcherModeKey{ "useTabSwitcher"
 static constexpr std::string_view TabSwitcherModeKey{ "tabSwitcherMode" };
 static constexpr std::string_view DisableAnimationsKey{ "disableAnimations" };
 static constexpr std::string_view StartupActionsKey{ "startupActions" };
+static constexpr std::string_view FocusFollowMouseKey{ "focusFollowMouse" };
 
 static constexpr std::string_view DebugFeaturesKey{ "debugFeatures" };
 
@@ -116,6 +117,7 @@ winrt::com_ptr<GlobalAppSettings> GlobalAppSettings::Copy() const
     globals->_TabSwitcherMode = _TabSwitcherMode;
     globals->_DisableAnimations = _DisableAnimations;
     globals->_StartupActions = _StartupActions;
+    globals->_FocusFollowMouse = _FocusFollowMouse;
 
     globals->_UnparsedDefaultProfile = _UnparsedDefaultProfile;
     globals->_validDefaultProfile = _validDefaultProfile;
@@ -304,6 +306,8 @@ void GlobalAppSettings::LayerJson(const Json::Value& json)
 
     JsonUtils::GetValueForKey(json, StartupActionsKey, _StartupActions);
 
+    JsonUtils::GetValueForKey(json, FocusFollowMouseKey, _FocusFollowMouse);
+
     // This is a helper lambda to get the keybindings and commands out of both
     // and array of objects. We'll use this twice, once on the legacy
     // `keybindings` key, and again on the newer `bindings` key.
@@ -399,6 +403,7 @@ Json::Value GlobalAppSettings::ToJson() const
     JsonUtils::SetValueForKey(json, TabSwitcherModeKey,             _TabSwitcherMode);
     JsonUtils::SetValueForKey(json, DisableAnimationsKey,           _DisableAnimations);
     JsonUtils::SetValueForKey(json, StartupActionsKey,              _StartupActions);
+    JsonUtils::SetValueForKey(json, FocusFollowMouseKey,            _FocusFollowMouse);
     // clang-format on
 
     // TODO GH#8100: keymap needs to be serialized here

src/cascadia/TerminalSettingsModel/GlobalAppSettings.h

@@ -87,6 +87,7 @@ namespace winrt::Microsoft::Terminal::Settings::Model::implementation
         GETSET_SETTING(Model::TabSwitcherMode, TabSwitcherMode, Model::TabSwitcherMode::InOrder);
         GETSET_SETTING(bool, DisableAnimations, false);
         GETSET_SETTING(hstring, StartupActions, L"");
+        GETSET_SETTING(bool, FocusFollowMouse, false);
 
     private:
         guid _defaultProfile;

src/cascadia/TerminalSettingsModel/GlobalAppSettings.idl

@@ -146,5 +146,9 @@ namespace Microsoft.Terminal.Settings.Model
         Boolean HasStartupActions();
         void ClearStartupActions();
         String StartupActions();
+
+        Boolean HasFocusFollowMouse();
+        void ClearFocusFollowMouse();
+        Boolean FocusFollowMouse;
     }
 }

src/cascadia/TerminalSettingsModel/defaults.json

@@ -27,6 +27,7 @@
     "snapToGridOnResize": true,
     "disableAnimations": false,
     "startupActions": "",
+    "focusFollowMouse": false,
 
     "profiles":
     [

src/cascadia/UnitTests_TerminalCore/MockTermSettings.h

@@ -35,6 +35,7 @@ namespace TerminalCoreUnitTests
         uint32_t CursorHeight() { return 42UL; }
         winrt::hstring WordDelimiters() { return winrt::hstring(DEFAULT_WORD_DELIMITERS); }
         bool CopyOnSelect() { return _copyOnSelect; }
+        bool FocusFollowMouse() { return _focusFollowMouse; }
         winrt::hstring StartingTitle() { return _startingTitle; }
         bool SuppressApplicationTitle() { return _suppressApplicationTitle; }
         uint32_t SelectionBackground() { return COLOR_WHITE; }
@@ -56,6 +57,7 @@ namespace TerminalCoreUnitTests
         void CursorHeight(uint32_t) {}
         void WordDelimiters(winrt::hstring) {}
         void CopyOnSelect(bool copyOnSelect) { _copyOnSelect = copyOnSelect; }
+        void FocusFollowMouse(bool focusFollowMouse) { _focusFollowMouse = focusFollowMouse; }
         void StartingTitle(winrt::hstring const& value) { _startingTitle = value; }
         void SuppressApplicationTitle(bool suppressApplicationTitle) { _suppressApplicationTitle = suppressApplicationTitle; }
         void SelectionBackground(uint32_t) {}
@@ -69,6 +71,7 @@ namespace TerminalCoreUnitTests
         int32_t _initialRows;
         int32_t _initialCols;
         bool _copyOnSelect{ false };
+        bool _focusFollowMouse{ false };
         bool _suppressApplicationTitle{ false };
         winrt::hstring _startingTitle;
     };