R6.12, R6.13: the LOK worker has no Dock icon; Show turns slides

R6.12: on macOS the worker sets LibreOffice's own NSApplication to the
accessory policy before the kit starts, so it never shows in the Dock.

R6.13: when the whole slide fits, the wheel and Up/Down (nothing
selected, no text editing) turn slides in the ElyShow editor.

Co-Authored-By: Claude Opus 5.5 (1M context) <noreply@anthropic.com>

apps/ely-show/src/slides.rs

@@ -9,10 +9,11 @@ use ely_gpui_component::{
 };
 use ely_office::prelude::*;
 use gpui::{
-    Action, App, Context, Div, InteractiveElement as _, IntoElement, Menu, MenuItem,
+    Action, App, Context, Div, Entity, InteractiveElement as _, IntoElement, Menu, MenuItem,
     ParentElement as _, Render, RenderImage, Role, StatefulInteractiveElement as _, Styled as _,
     WeakEntity, Window, actions, div, img, prelude::FluentBuilder as _, px,
 };
+use ely_lok::LokView;
 use image::{Frame, ImageBuffer, Rgba};
 
 use crate::deck::Deck;
@@ -98,6 +99,19 @@ impl Deck {
         self.run_active(id, &[], cx);
     }
 
+    /// Shows the slide `step` away, as the strip would.
+    pub(crate) fn turn(&mut self, id: u64, view: &Entity<LokView>, step: i32, cx: &mut Context<Self>) {
+        let Some(count) = self.tab(id).map(|tab| tab.extra.slides.list.len()).filter(|count| *count > 0) else {
+            return;
+        };
+        // From the part asked last, so quick turns add up.
+        let shown = view.read(cx).part();
+        let part = (shown as i64 + i64::from(step)).clamp(0, count as i64 - 1) as usize;
+        if part != shown {
+            view.update(cx, |view, _| view.show_part(part));
+        }
+    }
+
     /// Paints the next missing or stale slide picture.
     pub fn paint_next(&mut self, id: u64, cx: &mut Context<Self>) {
         let Some(tab) = self.tab(id) else {