Fix #434: action menu opens below trigger button via placement=Below

src/core/engine/mod.rs

@@ -1685,6 +1685,12 @@ pub struct ContextMenuState {
     pub selected: usize,
     pub screen_x: u16,
     pub screen_y: u16,
+    /// Height of the trigger element in line_height units (f32 so
+    /// backends with sub-cell row heights — e.g. GTK's tab row at
+    /// ceil(1.6 * line_height) — can place the menu flush against the
+    /// trigger). Non-zero opts into `ContextMenuPlacement::Below`
+    /// (#434); right-click flows leave this at 0.0 and use AnchorPoint.
+    pub trigger_height: f32,
 }
 
 /// One visible row in the flat explorer file-tree list.

src/core/engine/tests.rs

@@ -18381,7 +18381,7 @@ fn test_editor_action_menu_opens() {
     let mut e = Engine::new();
     e.buffer_mut().insert(0, "hello\n");
     let gid = e.active_group;
-    e.open_editor_action_menu(gid, 0, 0);
+    e.open_editor_action_menu(gid, 0, 0, 1.0);
     assert!(e.context_menu.is_some());
     let cm = e.context_menu.as_ref().unwrap();
     assert!(matches!(
@@ -18402,7 +18402,7 @@ fn test_editor_action_menu_close_others_disabled_with_one_tab() {
     let mut e = Engine::new();
     e.buffer_mut().insert(0, "hello\n");
     let gid = e.active_group;
-    e.open_editor_action_menu(gid, 0, 0);
+    e.open_editor_action_menu(gid, 0, 0, 1.0);
     let cm = e.context_menu.as_ref().unwrap();
     // "Close Others" disabled with only 1 tab.
     let close_others = cm
@@ -18422,7 +18422,7 @@ fn test_editor_action_menu_toggle_wrap() {
     e.buffer_mut().insert(0, "hello\n");
     let gid = e.active_group;
     assert!(!e.settings.wrap);
-    e.open_editor_action_menu(gid, 0, 0);
+    e.open_editor_action_menu(gid, 0, 0, 1.0);
     // Select "toggle_wrap" and confirm.
     if let Some(ref mut cm) = e.context_menu {
         if let Some(idx) = cm.items.iter().position(|i| i.action == "toggle_wrap") {
@@ -18442,7 +18442,7 @@ fn test_editor_action_menu_close_all() {
     e.new_tab(None);
     assert!(e.active_group().tabs.len() >= 2);
     let gid = e.active_group;
-    e.open_editor_action_menu(gid, 0, 0);
+    e.open_editor_action_menu(gid, 0, 0, 1.0);
     if let Some(ref mut cm) = e.context_menu {
         if let Some(idx) = cm.items.iter().position(|i| i.action == "close_all") {
             cm.selected = idx;

src/core/engine/windows.rs

@@ -691,11 +691,18 @@ impl Engine {
             selected,
             screen_x: x,
             screen_y: y,
+            trigger_height: 0.0,
         });
     }
 
     /// Open the editor action menu ("..." button) for a tab bar group.
-    pub fn open_editor_action_menu(&mut self, group_id: GroupId, x: u16, y: u16) {
+    pub fn open_editor_action_menu(
+        &mut self,
+        group_id: GroupId,
+        x: u16,
+        y: u16,
+        trigger_height: f32,
+    ) {
         let group = match self.editor_groups.get(&group_id) {
             Some(g) => g,
             None => return,
@@ -775,6 +782,7 @@ impl Engine {
             selected,
             screen_x: x,
             screen_y: y,
+            trigger_height,
         });
     }
 
@@ -957,6 +965,7 @@ impl Engine {
             selected: 0,
             screen_x: x,
             screen_y: y,
+            trigger_height: 0.0,
         });
     }
 
@@ -1041,6 +1050,7 @@ impl Engine {
             selected,
             screen_x: x,
             screen_y: y,
+            trigger_height: 0.0,
         });
     }
 

src/gtk/click.rs

@@ -324,7 +324,12 @@ pub(super) fn handle_mouse_click(
         ClickTarget::ActionMenuButton(group_id) => {
             let col = (x / char_width.max(1.0)) as u16;
             let row = (y / line_height.max(1.0)) as u16;
-            engine.open_editor_action_menu(group_id, col, row);
+            // #434: pass the trigger's exact height in line_height units so
+            // the menu sits flush against the button's bottom (no sub-cell
+            // gap). GTK's tab row is ceil(1.6 * line_height).
+            let trigger_h =
+                (render_mod::tab_row_height_px(line_height) / line_height.max(1.0)) as f32;
+            engine.open_editor_action_menu(group_id, col, row, trigger_h);
             (None, None)
         }
         _ => (None, None),

src/gtk/draw.rs

@@ -1956,10 +1956,19 @@ pub(super) fn draw_context_menu_popup(
 
     let anchor_x = cm.screen_col as f64 * char_width;
     let anchor_y = cm.screen_row as f64 * line_height;
+    let trigger_height_px = cm.trigger_height as f64 * line_height;
+    // trigger_height is in line_height units (f32 — see ContextMenuState
+    // docs). GTK's tab row is 1.6× line_height, so the caller passes 1.6
+    // for the action button and the menu sits flush against the button
+    // bottom (#434).
     let viewport = quadraui::Rect::new(0.0, 0.0, editor_width as f32, editor_height as f32);
-    let menu_layout = menu.layout(
-        anchor_x as f32,
-        anchor_y as f32,
+    let menu_layout = menu.layout_at(
+        quadraui::Rect::new(
+            anchor_x as f32,
+            anchor_y as f32,
+            0.0,
+            trigger_height_px as f32,
+        ),
         viewport,
         menu_w as f32,
         item_height,

src/render.rs

@@ -3559,6 +3559,11 @@ pub struct ContextMenuPanel {
     pub selected_idx: usize,
     pub screen_col: u16,
     pub screen_row: u16,
+    /// Trigger element height in line_height units (f32; supports
+    /// sub-cell rows like GTK's 1.6× tab row). 0.0 = no trigger →
+    /// render at click coords (AnchorPoint). Non-zero opts into
+    /// `ContextMenuPlacement::Below` (#434).
+    pub trigger_height: f32,
 }
 
 /// A single rendered context menu item.
@@ -3607,12 +3612,17 @@ pub fn context_menu_panel_to_quadraui_context_menu(
         .get(panel.selected_idx)
         .copied()
         .unwrap_or(0);
+    let placement = if panel.trigger_height > 0.0 {
+        quadraui::ContextMenuPlacement::Below
+    } else {
+        quadraui::ContextMenuPlacement::AnchorPoint
+    };
     quadraui::ContextMenu {
         id: quadraui::WidgetId::new("context_menu"),
         items,
         selected_idx,
         bg: None,
-        placement: quadraui::ContextMenuPlacement::default(),
+        placement,
     }
 }
 
@@ -6215,6 +6225,7 @@ pub fn build_screen_layout(
             selected_idx: cm.selected,
             screen_col: cm.screen_x,
             screen_row: cm.screen_y,
+            trigger_height: cm.trigger_height,
         }),
         find_replace: if engine.find_replace_open {
             let match_info = if engine.search_matches.is_empty() {

src/tui_main/mouse.rs

@@ -2524,7 +2524,10 @@ pub(super) fn handle_mouse(
                         }
                         TabBarClickTarget::ActionMenu => {
                             engine.active_group = group_id;
-                            engine.open_editor_action_menu(group_id, col, row + 1);
+                            // #434: pass tab-row height (1.0 row in TUI) so the
+                            // engine drives Below placement; replaces the prior
+                            // `row + 1` hack.
+                            engine.open_editor_action_menu(group_id, col, row, 1.0);
                         }
                         _ => {
                             engine.handle_tab_bar_click(group_id, target);
@@ -2610,7 +2613,8 @@ pub(super) fn handle_mouse(
                             engine.open_editor_group(SplitDirection::Horizontal);
                         }
                         "tab:action_menu" => {
-                            engine.open_editor_action_menu(engine.active_group, col, row + 1);
+                            // #434: pass tab-row height (1.0 row in TUI).
+                            engine.open_editor_action_menu(engine.active_group, col, row, 1.0);
                         }
                         _ => {}
                     }

src/tui_main/render_impl.rs

@@ -968,9 +968,13 @@ pub(super) fn draw_frame(
             .unwrap_or(0);
         let outer_width = (max_label + max_shortcut + 6).clamp(20, 50) as f32;
         let inner_width = (outer_width - 2.0).max(1.0);
-        let layout = menu.layout(
-            ctx_menu.screen_col as f32 + 1.0,
-            ctx_menu.screen_row as f32 + 1.0,
+        let layout = menu.layout_at(
+            quadraui::Rect::new(
+                ctx_menu.screen_col as f32 + 1.0,
+                ctx_menu.screen_row as f32 + 1.0,
+                0.0,
+                ctx_menu.trigger_height,
+            ),
             inner_viewport,
             inner_width,
             |_| quadraui::ContextMenuItemMeasure::new(1.0),