navigation: selectable mouse navigation style

Options → User Preferences → Navigation style picks which mouse
gestures pan and orbit the model view (#1480):

- CAD (default): middle button pans, Shift + middle button orbits.
- Blender: middle button orbits, Shift + middle button pans.
- CATIA: middle button pans; pressing the left button during it orbits,
  so 3D navigation needs only the mouse.

An armed orbit tool always orbits. The choice is saved with the user
settings.

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

locales/ar-SA/opencadstudio.ftl

@@ -1563,6 +1563,10 @@ common =
     .user-preferences = تفضيلات المستخدم
     .zoom = التكبير
     .reverse-mouse-wheel-zoom-zoomwheel = عكس التكبير بعجلة الفأرة (ZOOMWHEEL)
+    .navigation-style = نمط التنقل
+    .nav-style-cad = CAD: ‏Shift + الزر الأوسط للدوران
+    .nav-style-blender = Blender: الزر الأوسط للدوران، Shift للتحريك
+    .nav-style-catia = CATIA: الزر الأوسط + الأيسر للدوران
     .touchpad-scroll-pans-ctrl-scroll-or-pinch-zooms = لوحة اللمس: التمرير يحرك العرض، Ctrl+تمرير أو القرص يكبّر
     .interface-scale = مقياس الواجهة
     .zoom-factor = معامل التكبير

locales/bg-BG/opencadstudio.ftl

@@ -1550,6 +1550,10 @@ common =
     .user-preferences = Потребителски предпочитания
     .zoom = Мащабиране
     .reverse-mouse-wheel-zoom-zoomwheel = Обръщане на мащабирането с колелцето (ZOOMWHEEL)
+    .navigation-style = Стил на навигация
+    .nav-style-cad = CAD: Shift + среден бутон завърта
+    .nav-style-blender = Blender: среден бутон завърта, Shift премества
+    .nav-style-catia = CATIA: среден + ляв бутон завърта
     .touchpad-scroll-pans-ctrl-scroll-or-pinch-zooms = Тъчпад: превъртането мести изгледа, Ctrl+превъртане или щипване мащабира
     .interface-scale = Мащаб на интерфейса
     .zoom-factor = Коефициент на мащабиране

locales/cs-CZ/opencadstudio.ftl

@@ -1550,6 +1550,10 @@ common =
     .user-preferences = Předvolby uživatele
     .zoom = Zoom
     .reverse-mouse-wheel-zoom-zoomwheel = Obrátit zoom kolečkem myši (ZOOMWHEEL)
+    .navigation-style = Styl navigace
+    .nav-style-cad = CAD: Shift + prostřední tlačítko otáčí
+    .nav-style-blender = Blender: prostřední tlačítko otáčí, Shift posouvá
+    .nav-style-catia = CATIA: prostřední + levé tlačítko otáčí
     .touchpad-scroll-pans-ctrl-scroll-or-pinch-zooms = Touchpad: posun posouvá pohled, Ctrl+posun nebo sevření zvětšuje
     .interface-scale = Měřítko rozhraní
     .zoom-factor = Faktor zoomu

locales/de-DE/opencadstudio.ftl

@@ -1551,6 +1551,10 @@ common =
     .user-preferences = Benutzereinstellungen
     .zoom = Zoom
     .reverse-mouse-wheel-zoom-zoomwheel = Mausradzoom umkehren (ZOOMWHEEL)
+    .navigation-style = Navigationsstil
+    .nav-style-cad = CAD: Umschalt + mittlere Taste dreht
+    .nav-style-blender = Blender: mittlere Taste dreht, Umschalt verschiebt
+    .nav-style-catia = CATIA: mittlere + linke Taste dreht
     .touchpad-scroll-pans-ctrl-scroll-or-pinch-zooms = Touchpad: Scrollen verschiebt, Strg+Scrollen oder Zusammenziehen zoomt
     .interface-scale = Oberflächenskalierung
     .zoom-factor = Zoomfaktor

locales/el-GR/opencadstudio.ftl

@@ -1552,6 +1552,10 @@ common =
     .user-preferences = Προτιμήσεις χρήστη
     .zoom = Ζουμ
     .reverse-mouse-wheel-zoom-zoomwheel = Αντιστροφή ζουμ με τον τροχό (ZOOMWHEEL)
+    .navigation-style = Στυλ πλοήγησης
+    .nav-style-cad = CAD: Shift + μεσαίο πλήκτρο περιστρέφει
+    .nav-style-blender = Blender: μεσαίο πλήκτρο περιστρέφει, Shift μετακινεί
+    .nav-style-catia = CATIA: μεσαίο + αριστερό πλήκτρο περιστρέφει
     .touchpad-scroll-pans-ctrl-scroll-or-pinch-zooms = Επιφάνεια αφής: η κύλιση μετακινεί, Ctrl+κύλιση ή τσίμπημα κάνει ζουμ
     .interface-scale = Κλίμακα διεπαφής
     .zoom-factor = Συντελεστής ζουμ

locales/en-US/opencadstudio.ftl

@@ -1551,6 +1551,10 @@ common =
     .user-preferences = User Preferences
     .zoom = Zoom
     .reverse-mouse-wheel-zoom-zoomwheel = Reverse mouse wheel zoom (ZOOMWHEEL)
+    .navigation-style = Navigation style
+    .nav-style-cad = CAD: Shift + middle button orbits
+    .nav-style-blender = Blender: middle button orbits, Shift pans
+    .nav-style-catia = CATIA: middle + left button orbits
     .touchpad-scroll-pans-ctrl-scroll-or-pinch-zooms = Touchpad: scroll pans, Ctrl+scroll or pinch zooms
     .interface-scale = Interface scale
     .zoom-factor = Zoom factor

locales/es-ES/opencadstudio.ftl

@@ -1551,6 +1551,10 @@ common =
     .user-preferences = Preferencias de usuario
     .zoom = Zoom
     .reverse-mouse-wheel-zoom-zoomwheel = Invertir el zoom de la rueda del ratón (ZOOMWHEEL)
+    .navigation-style = Estilo de navegación
+    .nav-style-cad = CAD: Mayús + botón central orbita
+    .nav-style-blender = Blender: botón central orbita, Mayús desplaza
+    .nav-style-catia = CATIA: botón central + izquierdo orbita
     .touchpad-scroll-pans-ctrl-scroll-or-pinch-zooms = Panel táctil: el desplazamiento encuadra, Ctrl+desplazamiento o pellizco hace zoom
     .interface-scale = Escala de la interfaz
     .zoom-factor = Factor de zoom

locales/fi-FI/opencadstudio.ftl

@@ -1550,6 +1550,10 @@ common =
     .user-preferences = Käyttäjäasetukset
     .zoom = Zoomaus
     .reverse-mouse-wheel-zoom-zoomwheel = Käännä hiiren rullan zoomaus (ZOOMWHEEL)
+    .navigation-style = Navigointityyli
+    .nav-style-cad = CAD: Vaihto + keskipainike kiertää
+    .nav-style-blender = Blender: keskipainike kiertää, Vaihto panoroi
+    .nav-style-catia = CATIA: keski- + vasen painike kiertää
     .touchpad-scroll-pans-ctrl-scroll-or-pinch-zooms = Kosketuslevy: vieritys panoroi, Ctrl+vieritys tai nipistys zoomaa
     .interface-scale = Käyttöliittymän skaalaus
     .zoom-factor = Zoomauskerroin

locales/fr-FR/opencadstudio.ftl

@@ -1551,6 +1551,10 @@ common =
     .user-preferences = Préférences utilisateur
     .zoom = Zoom
     .reverse-mouse-wheel-zoom-zoomwheel = Inverser le zoom à la molette (ZOOMWHEEL)
+    .navigation-style = Style de navigation
+    .nav-style-cad = CAO : Maj + bouton du milieu fait pivoter
+    .nav-style-blender = Blender : bouton du milieu fait pivoter, Maj déplace
+    .nav-style-catia = CATIA : boutons du milieu + gauche font pivoter
     .touchpad-scroll-pans-ctrl-scroll-or-pinch-zooms = Pavé tactile : le défilement déplace, Ctrl+défilement ou pincement zoome
     .interface-scale = Échelle de l'interface
     .zoom-factor = Facteur de zoom

locales/hi-IN/opencadstudio.ftl

@@ -1539,6 +1539,10 @@ common =
     .user-preferences = उपयोगकर्ता प्राथमिकताएँ
     .zoom = ज़ूम
     .reverse-mouse-wheel-zoom-zoomwheel = माउस व्हील ज़ूम उलटें (ZOOMWHEEL)
+    .navigation-style = नेविगेशन शैली
+    .nav-style-cad = CAD: Shift + मध्य बटन घुमाता है
+    .nav-style-blender = Blender: मध्य बटन घुमाता है, Shift खिसकाता है
+    .nav-style-catia = CATIA: मध्य + बायाँ बटन घुमाता है
     .touchpad-scroll-pans-ctrl-scroll-or-pinch-zooms = टचपैड: स्क्रॉल पैन करता है, Ctrl+स्क्रॉल या पिंच ज़ूम करता है
     .interface-scale = इंटरफ़ेस स्केल
     .zoom-factor = ज़ूम गुणक

locales/hu-HU/opencadstudio.ftl

@@ -1556,6 +1556,10 @@ common =
     .user-preferences = Felhasználói beállítások
     .zoom = Nagyítás
     .reverse-mouse-wheel-zoom-zoomwheel = Egérgörgős nagyítás megfordítása (ZOOMWHEEL)
+    .navigation-style = Navigációs stílus
+    .nav-style-cad = CAD: Shift + középső gomb forgat
+    .nav-style-blender = Blender: középső gomb forgat, Shift mozgat
+    .nav-style-catia = CATIA: középső + bal gomb forgat
     .touchpad-scroll-pans-ctrl-scroll-or-pinch-zooms = Érintőpad: a görgetés mozgat, a Ctrl+görgetés vagy csippentés nagyít
     .interface-scale = Felület mérete
     .zoom-factor = Nagyítási tényező

locales/it-IT/opencadstudio.ftl

@@ -1550,6 +1550,10 @@ common =
     .user-preferences = Preferenze utente
     .zoom = Zoom
     .reverse-mouse-wheel-zoom-zoomwheel = Inverti lo zoom con la rotellina (ZOOMWHEEL)
+    .navigation-style = Stile di navigazione
+    .nav-style-cad = CAD: Maiusc + tasto centrale ruota
+    .nav-style-blender = Blender: tasto centrale ruota, Maiusc sposta
+    .nav-style-catia = CATIA: tasto centrale + sinistro ruota
     .touchpad-scroll-pans-ctrl-scroll-or-pinch-zooms = Touchpad: lo scorrimento sposta la vista, Ctrl+scorrimento o pizzico esegue lo zoom
     .interface-scale = Scala dell'interfaccia
     .zoom-factor = Fattore di zoom

locales/ja-JP/opencadstudio.ftl

@@ -1541,6 +1541,10 @@ common =
     .user-preferences = ユーザー設定
     .zoom = ズーム
     .reverse-mouse-wheel-zoom-zoomwheel = マウス ホイールのズーム方向を反転 (ZOOMWHEEL)
+    .navigation-style = ナビゲーション スタイル
+    .nav-style-cad = CAD: Shift + 中ボタンで回転
+    .nav-style-blender = Blender: 中ボタンで回転、Shift で画面移動
+    .nav-style-catia = CATIA: 中 + 左ボタンで回転
     .touchpad-scroll-pans-ctrl-scroll-or-pinch-zooms = タッチパッド: スクロールで画面移動、Ctrl+スクロールまたはピンチでズーム
     .interface-scale = インターフェースの拡大率
     .zoom-factor = ズーム倍率

locales/ko-KR/opencadstudio.ftl

@@ -1550,6 +1550,10 @@ common =
     .user-preferences = 사용자 환경설정
     .zoom = 줌
     .reverse-mouse-wheel-zoom-zoomwheel = 마우스 휠 줌 방향 반전 (ZOOMWHEEL)
+    .navigation-style = 탐색 스타일
+    .nav-style-cad = CAD: Shift + 가운데 버튼으로 회전
+    .nav-style-blender = Blender: 가운데 버튼으로 회전, Shift로 이동
+    .nav-style-catia = CATIA: 가운데 + 왼쪽 버튼으로 회전
     .touchpad-scroll-pans-ctrl-scroll-or-pinch-zooms = 터치패드: 스크롤은 화면 이동, Ctrl+스크롤 또는 핀치는 확대/축소
     .interface-scale = 인터페이스 배율
     .zoom-factor = 줌 배율

locales/lo-LA/opencadstudio.ftl

@@ -1556,6 +1556,10 @@ common =
     .user-preferences = ການຕັ້ງຄ່າສ່ວນຕົວຂອງຜູ້ໃຊ້
     .zoom = ຊູມ
     .reverse-mouse-wheel-zoom-zoomwheel = ສະຫຼັບທິດທາງການໝຸນລໍ້ເມົາສ໌ຊູມ (ZOOMWHEEL)
+    .navigation-style = ຮູບແບບການນຳທາງ
+    .nav-style-cad = CAD: Shift + ປຸ່ມກາງ ໝຸນ
+    .nav-style-blender = Blender: ປຸ່ມກາງ ໝຸນ, Shift ເລື່ອນ
+    .nav-style-catia = CATIA: ປຸ່ມກາງ + ຊ້າຍ ໝຸນ
     .touchpad-scroll-pans-ctrl-scroll-or-pinch-zooms = ທັດແພດ: ເລື່ອນເພື່ອຍ້າຍມຸມມອງ, Ctrl+ເລື່ອນ ຫຼື ບີບເພື່ອຊູມ
     .interface-scale = ຂະໜາດສ່ວນຕິດຕໍ່
     .zoom-factor = ຕົວຄູນການຊູມ

locales/nl-NL/opencadstudio.ftl

@@ -1549,6 +1549,10 @@ common =
     .user-preferences = Gebruikersvoorkeuren
     .zoom = Zoomen
     .reverse-mouse-wheel-zoom-zoomwheel = Muiswielzoom omkeren (ZOOMWHEEL)
+    .navigation-style = Navigatiestijl
+    .nav-style-cad = CAD: Shift + middelste knop draait
+    .nav-style-blender = Blender: middelste knop draait, Shift verschuift
+    .nav-style-catia = CATIA: middelste + linkerknop draait
     .touchpad-scroll-pans-ctrl-scroll-or-pinch-zooms = Touchpad: scrollen verschuift, Ctrl+scrollen of knijpen zoomt
     .interface-scale = Interfaceschaal
     .zoom-factor = Zoomfactor

locales/pl-PL/opencadstudio.ftl

@@ -1550,6 +1550,10 @@ common =
     .user-preferences = Preferencje użytkownika
     .zoom = Powiększenie
     .reverse-mouse-wheel-zoom-zoomwheel = Odwróć powiększanie kółkiem myszy (ZOOMWHEEL)
+    .navigation-style = Styl nawigacji
+    .nav-style-cad = CAD: Shift + środkowy przycisk obraca
+    .nav-style-blender = Blender: środkowy przycisk obraca, Shift przesuwa
+    .nav-style-catia = CATIA: środkowy + lewy przycisk obraca
     .touchpad-scroll-pans-ctrl-scroll-or-pinch-zooms = Touchpad: przewijanie przesuwa widok, Ctrl+przewijanie lub szczypanie powiększa
     .interface-scale = Skala interfejsu
     .zoom-factor = Współczynnik powiększenia

locales/pt-BR/opencadstudio.ftl

@@ -1551,6 +1551,10 @@ common =
     .user-preferences = Preferências do usuário
     .zoom = Zoom
     .reverse-mouse-wheel-zoom-zoomwheel = Inverter o zoom da roda do mouse (ZOOMWHEEL)
+    .navigation-style = Estilo de navegação
+    .nav-style-cad = CAD: Shift + botão do meio orbita
+    .nav-style-blender = Blender: botão do meio orbita, Shift desloca
+    .nav-style-catia = CATIA: botão do meio + esquerdo orbita
     .touchpad-scroll-pans-ctrl-scroll-or-pinch-zooms = Touchpad: rolar move a vista, Ctrl+rolar ou pinçar aplica zoom
     .interface-scale = Escala da interface
     .zoom-factor = Fator de zoom

locales/ru-RU/opencadstudio.ftl

@@ -1554,6 +1554,10 @@ common =
     .user-preferences = Пользовательские настройки
     .zoom = Зумирование
     .reverse-mouse-wheel-zoom-zoomwheel = Обратить зумирование колесом мыши (ZOOMWHEEL)
+    .navigation-style = Стиль навигации
+    .nav-style-cad = CAD: Shift + средняя кнопка — вращение
+    .nav-style-blender = Blender: средняя кнопка — вращение, Shift — сдвиг
+    .nav-style-catia = CATIA: средняя + левая кнопка — вращение
     .touchpad-scroll-pans-ctrl-scroll-or-pinch-zooms = Тачпад: прокрутка панорамирует, Ctrl+прокрутка или щипок масштабирует
     .interface-scale = Масштаб интерфейса
     .zoom-factor = Коэффициент зумирования

locales/tr-TR/opencadstudio.ftl

@@ -1537,6 +1537,10 @@ common =
     .user-preferences = Kullanıcı tercihleri
     .zoom = Yakınlaştırma
     .reverse-mouse-wheel-zoom-zoomwheel = Fare tekerleği yakınlaştırmasını ters çevir (ZOOMWHEEL)
+    .navigation-style = Gezinme stili
+    .nav-style-cad = CAD: Shift + orta tuş döndürür
+    .nav-style-blender = Blender: orta tuş döndürür, Shift kaydırır
+    .nav-style-catia = CATIA: orta + sol tuş döndürür
     .touchpad-scroll-pans-ctrl-scroll-or-pinch-zooms = Dokunmatik yüzey: kaydırma kaydırır, Ctrl+kaydırma veya sıkıştırma yakınlaştırır
     .interface-scale = Arayüz ölçeği
     .zoom-factor = Yakınlaştırma çarpanı

locales/zh-CN/opencadstudio.ftl

@@ -1538,6 +1538,10 @@ common =
     .user-preferences = 用户首选项
     .zoom = 缩放
     .reverse-mouse-wheel-zoom-zoomwheel = 反转鼠标滚轮缩放方向 (ZOOMWHEEL)
+    .navigation-style = 导航样式
+    .nav-style-cad = CAD：Shift + 中键旋转
+    .nav-style-blender = Blender：中键旋转，Shift 平移
+    .nav-style-catia = CATIA：中键 + 左键旋转
     .touchpad-scroll-pans-ctrl-scroll-or-pinch-zooms = 触控板：滚动平移，Ctrl+滚动或捏合缩放
     .interface-scale = 界面缩放
     .zoom-factor = 缩放系数

locales/zh-TW/opencadstudio.ftl

@@ -1550,6 +1550,10 @@ common =
     .user-preferences = 使用者偏好設定
     .zoom = 縮放
     .reverse-mouse-wheel-zoom-zoomwheel = 反轉滑鼠滾輪縮放方向 (ZOOMWHEEL)
+    .navigation-style = 導覽樣式
+    .nav-style-cad = CAD：Shift + 中鍵旋轉
+    .nav-style-blender = Blender：中鍵旋轉，Shift 平移
+    .nav-style-catia = CATIA：中鍵 + 左鍵旋轉
     .touchpad-scroll-pans-ctrl-scroll-or-pinch-zooms = 觸控板：捲動平移，Ctrl+捲動或捏合縮放
     .interface-scale = 介面縮放
     .zoom-factor = 縮放係數

src/app/mod.rs

@@ -650,6 +650,11 @@ pub(super) struct OpenCADStudio {
     polar_increment_deg: f32,
     /// Reverse the mouse-wheel zoom direction when true (ZOOMWHEEL = 1).
     zoom_wheel_reversed: bool,
+    /// Which mouse gestures pan and orbit the model view.
+    navigation_style: crate::app::settings::NavigationStyle,
+    /// CATIA navigation: the left button went down while the middle one was
+    /// held, so the middle drag orbits until it is released.
+    nav_left_with_middle: bool,
     /// Scroll pans and Ctrl+scroll zooms (touchpads); see `scroll_intent`.
     touchpad_pan: bool,
     /// Multi-finger gestures on a touch screen.
@@ -2657,6 +2662,7 @@ pub enum Message {
     CommandLineOpacityChanged(u8),
     /// Toggle reversing the mouse-wheel zoom direction (ZOOMWHEEL).
     ZoomWheelReversedChanged(bool),
+    NavigationStyleChanged(crate::app::settings::NavigationStyle),
     TouchpadPanChanged(bool),
     /// Options: show the pull-down menus (MENUBAR).
     MenuBarChanged(bool),
@@ -4632,6 +4638,8 @@ impl OpenCADStudio {
             polar_mode: false,
             polar_increment_deg: 45.0,
             zoom_wheel_reversed: false,
+            navigation_style: Default::default(),
+            nav_left_with_middle: false,
             touchpad_pan: false,
             touch: Default::default(),
             touch_offset: None,

src/app/settings.rs

@@ -204,6 +204,33 @@ pub fn zoom_notch_percent(factor: i32) -> f32 {
     (1.0 - ratio) * 100.0
 }
 
+/// Which mouse gestures pan and orbit the model view.
+#[derive(Clone, Copy, Debug, Default, PartialEq, Eq, Serialize, Deserialize)]
+#[serde(rename_all = "snake_case")]
+pub enum NavigationStyle {
+    /// Middle button pans; Shift + middle button orbits.
+    #[default]
+    Cad,
+    /// Middle button orbits; Shift + middle button pans.
+    Blender,
+    /// Middle button pans; middle and left buttons together orbit.
+    Catia,
+}
+
+impl NavigationStyle {
+    pub const ALL: [NavigationStyle; 3] = [Self::Cad, Self::Blender, Self::Catia];
+}
+
+impl std::fmt::Display for NavigationStyle {
+    fn fmt(&self, f: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {
+        f.write_str(&match self {
+            Self::Cad => crate::t!("CAD: Shift + middle button orbits"),
+            Self::Blender => crate::t!("Blender: middle button orbits, Shift pans"),
+            Self::Catia => crate::t!("CATIA: middle + left button orbits"),
+        })
+    }
+}
+
 /// Active pair of axes while isometric drafting is enabled.
 #[derive(Clone, Copy, Debug, Default, PartialEq, Eq, Serialize, Deserialize)]
 pub enum IsoPlane {
@@ -388,6 +415,7 @@ pub struct UserSettings {
     pub polar: bool,
     pub polar_increment_deg: f32,
     pub zoom_wheel_reversed: bool,
+    pub navigation_style: NavigationStyle,
     /// Scrolling pans and Ctrl+scroll (a touchpad pinch) zooms, for a
     /// touchpad that reports two-finger drags as wheel scrolls.
     pub touchpad_pan: bool,
@@ -891,6 +919,7 @@ impl Default for UserSettings {
             polar: false,
             polar_increment_deg: 45.0,
             zoom_wheel_reversed: false,
+            navigation_style: NavigationStyle::Cad,
             touchpad_pan: false,
             ui_scale_percent: 100,
             zoom_factor: 60,

src/app/update/file.rs

@@ -778,6 +778,7 @@ impl OpenCADStudio {
             polar: self.polar_mode,
             polar_increment_deg: self.polar_increment_deg,
             zoom_wheel_reversed: self.zoom_wheel_reversed,
+            navigation_style: self.navigation_style,
             touchpad_pan: self.touchpad_pan,
             ui_scale_percent: self.ui_scale_percent,
             zoom_factor: self.zoom_factor,
@@ -913,6 +914,7 @@ impl OpenCADStudio {
         self.polar_mode = s.polar;
         self.polar_increment_deg = s.polar_increment_deg;
         self.zoom_wheel_reversed = s.zoom_wheel_reversed;
+        self.navigation_style = s.navigation_style;
         self.touchpad_pan = s.touchpad_pan;
         self.ui_scale_percent = crate::app::settings::clamp_ui_scale(s.ui_scale_percent);
         self.zoom_factor = crate::app::settings::clamp_zoom_factor(s.zoom_factor);

src/app/update/mod.rs

@@ -4482,6 +4482,25 @@ impl OpenCADStudio {
                 Task::none()
             }
 
+            // CATIA navigation: the left button pressed during a middle drag
+            // turns the drag into an orbit instead of starting a pick.
+            Message::ViewportLeftPressAt(_) | Message::ViewportLeftPress | Message::PanePress(_)
+                if self.navigation_style == crate::app::settings::NavigationStyle::Catia
+                    && self.tabs[self.active_tab]
+                        .scene
+                        .selection
+                        .borrow()
+                        .input
+                        .middle_down =>
+            {
+                self.nav_left_with_middle = true;
+                Task::none()
+            }
+            Message::ViewportLeftRelease | Message::PaneRelease(_) if self.nav_left_with_middle => {
+                self.nav_left_with_middle = false;
+                Task::none()
+            }
+
             Message::ViewportMove(p) => self.on_viewport_move(p),
 
             Message::ViewportExit => self.on_viewport_exit(),
@@ -4686,6 +4705,7 @@ impl OpenCADStudio {
             }
 
             Message::ViewportMiddleRelease => {
+                self.nav_left_with_middle = false;
                 let i = self.active_tab;
                 let mut sel = self.tabs[i].scene.selection.borrow_mut();
                 sel.input.middle_down = false;
@@ -9225,6 +9245,12 @@ impl OpenCADStudio {
                 Task::none()
             }
 
+            Message::NavigationStyleChanged(style) => {
+                self.navigation_style = style;
+                self.persist_settings_if_changed();
+                Task::none()
+            }
+
             Message::MenuBarChanged(shown) => {
                 self.show_menu_bar = shown;
                 self.persist_settings_if_changed();

src/app/update/viewport.rs

@@ -1416,7 +1416,7 @@ impl OpenCADStudio {
                 // — the requested Zoom=wheel / Pan=MMB / Rotate=Shift+MMB
                 // scheme (#229). Floating viewports and paper keep the
                 // plain MMB pan.
-                if self.shift_down || self.tabs[i].orbit_mode {
+                if self.middle_drag_orbits(i) {
                     if self.tabs[i].scene.active_viewport.is_some() {
                         // Orbit the floating viewport's own model view.
                         drop(sel);
@@ -3165,6 +3165,18 @@ impl OpenCADStudio {
         Task::none()
     }
 
+    /// Whether a middle-button drag orbits rather than pans, by the
+    /// navigation style (an armed orbit tool always orbits).
+    fn middle_drag_orbits(&self, i: usize) -> bool {
+        use crate::app::settings::NavigationStyle;
+        self.tabs[i].orbit_mode
+            || match self.navigation_style {
+                NavigationStyle::Cad => self.shift_down,
+                NavigationStyle::Blender => !self.shift_down,
+                NavigationStyle::Catia => self.nav_left_with_middle,
+            }
+    }
+
     pub(crate) fn on_viewport_exit(&mut self) -> Task<Message> {
         let i = self.active_tab;
         self.tabs[i].measurement.live_visible = false;

src/app/view/modal.rs

@@ -312,6 +312,7 @@ impl OpenCADStudio {
                             show_ribbon: !self.ribbon_closed,
                             hatch_associative: self.hatch_associative,
                             zoom_wheel_reversed: self.zoom_wheel_reversed,
+                            navigation_style: self.navigation_style,
                             touchpad_pan: self.touchpad_pan,
                             ui_scale_percent: self.ui_scale_percent,
                             zoom_factor: self.zoom_factor,

src/locale_catalog.rs

@@ -5070,6 +5070,10 @@ pub(super) fn message_attribute(source: &str) -> Option<(&'static str, &'static
         "User Preferences" => Some(("common", "user-preferences")),
         "Zoom" => Some(("common", "zoom")),
         "Reverse mouse wheel zoom (ZOOMWHEEL)" => Some(("common", "reverse-mouse-wheel-zoom-zoomwheel")),
+        "Navigation style" => Some(("common", "navigation-style")),
+        "CAD: Shift + middle button orbits" => Some(("common", "nav-style-cad")),
+        "Blender: middle button orbits, Shift pans" => Some(("common", "nav-style-blender")),
+        "CATIA: middle + left button orbits" => Some(("common", "nav-style-catia")),
         "Touchpad: scroll pans, Ctrl+scroll or pinch zooms" => Some(("common", "touchpad-scroll-pans-ctrl-scroll-or-pinch-zooms")),
         "Interface scale" => Some(("common", "interface-scale")),
         "Zoom factor" => Some(("common", "zoom-factor")),

src/ui/window/options.rs

@@ -63,6 +63,8 @@ pub struct AppPrefs {
     pub hatch_associative: bool,
     /// ZOOMWHEEL: reverse the mouse-wheel zoom direction.
     pub zoom_wheel_reversed: bool,
+    /// Which mouse gestures pan and orbit the model view.
+    pub navigation_style: crate::app::settings::NavigationStyle,
     /// Scroll pans and Ctrl+scroll zooms (touchpads).
     pub touchpad_pan: bool,
     /// Interface scale in percent.
@@ -1274,6 +1276,16 @@ pub fn view_window<'a>(
         Space::new().height(10),
         spacemouse,
         Space::new().height(12),
+        text(crate::t!("Navigation style")).size(15),
+        Space::new().height(10),
+        iced::widget::pick_list(
+            Some(prefs.navigation_style),
+            crate::app::settings::NavigationStyle::ALL,
+            |style| style.to_string(),
+        )
+        .on_select(Message::NavigationStyleChanged)
+        .text_size(12),
+        Space::new().height(12),
         text(crate::t!("Zoom")).size(15),
         Space::new().height(10),
         row![