Scroll long menus and lists with the mouse wheel or a swipe

Touch clicks in menus happen on release without a swipe. The first-start
language picker is a flag grid that scrolls.

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

src/main.rs

@@ -842,6 +842,8 @@ async fn main() {
     let mut inp = Input { ldown: None, rdown: None, rlast: (0.0, 0.0), rdrag: false, mlast: None, minimap_drag: false, tlast: None, touch_world: false, inspect: None };
     let mut touch = TouchInput::new();
     let mut auto_touch = platform::coarse_pointer();
+    let mut menu_swipe: Option<(f32, f32)> = None; // a swipe over a menu: last finger y, unused distance
+    let mut menu_dragged = false; // the finger on a menu has swiped (no click when it lifts)
     // until the mouse has really moved its position is (0, 0): no edge scrolling before that
     let mut mouse_moved = false; // automatic mode: touch interface after a touch, desktop after a mouse click
     let mut autosave_t = 0.0f32;
@@ -1025,11 +1027,45 @@ async fn main() {
             }
         }
         let (_, wheel) = mouse_wheel();
-        if wheel != 0.0 && menu.page.is_some() {
-            let d = if wheel > 0.0 { -1 } else { 1 };
-            // an open language dropdown scrolls first
-            if !menu.lang_wheel(d) && menu.scrollable() {
-                menu.scroll_lines(d);
+        if wheel != 0.0 && ui.show_langsel {
+            ui.langsel_wheel(if wheel > 0.0 { -1 } else { 1 });
+        } else if wheel != 0.0 && menu.page.is_some() {
+            menu.wheel(if wheel > 0.0 { -1 } else { 1 });
+        } else if wheel != 0.0 {
+            ui.overview_wheel(ux, uy, if wheel > 0.0 { -1 } else { 1 });
+        }
+        // touch: a swipe over a menu, the language grid or the creature overview scrolls it,
+        // one line per row height
+        if touch_mode {
+            for g in &gestures {
+                match *g {
+                    Gesture::Press(_) => menu_dragged = false,
+                    Gesture::DragStart(p) if menu.page.is_some() || ui.show_langsel || ui.overview_wheel(p.x, p.y, 0) => {
+                        menu_swipe = Some((p.y, 0.0));
+                        menu_dragged = true;
+                    }
+                    Gesture::DragMove(p) => {
+                        if let Some((last, acc)) = menu_swipe {
+                            let mut acc = acc + p.y - last;
+                            let step = ui::CH() * 2.0;
+                            while acc.abs() >= step {
+                                // finger up: the content follows it up, so the list scrolls down
+                                let d = if acc < 0.0 { 1 } else { -1 };
+                                if ui.show_langsel {
+                                    ui.langsel_wheel(d);
+                                } else if menu.page.is_some() {
+                                    menu.wheel(d);
+                                } else {
+                                    ui.overview_wheel(p.x, p.y, d);
+                                }
+                                acc += d as f32 * step;
+                            }
+                            menu_swipe = Some((p.y, acc));
+                        }
+                    }
+                    Gesture::DragEnd | Gesture::Cancel => menu_swipe = None,
+                    _ => {}
+                }
             }
         }
 
@@ -1269,7 +1305,16 @@ async fn main() {
         }
 
         // ---------------- left button (touch: a finger touching the interface)
-        let pressed = if touch_mode { gestures.iter().any(|g| matches!(g, Gesture::Press(_))) } else { is_mouse_button_pressed(MouseButton::Left) };
+        // (in menus and dialogs a touch clicks when the finger lifts without a swipe, so that
+        // swiping a list scrolls it instead of picking the entry under the finger)
+        let menu_touch = touch_mode && (in_menu || dialog);
+        let pressed = if menu_touch {
+            !menu_dragged && gestures.iter().any(|g| matches!(g, Gesture::Release(_)))
+        } else if touch_mode {
+            gestures.iter().any(|g| matches!(g, Gesture::Press(_)))
+        } else {
+            is_mouse_button_pressed(MouseButton::Left)
+        };
         if touch_mode && pressed {
             inp.touch_world = playing && !over_ui;
             inp.inspect = None;