Tidy up after the sizing rework

The caps model landed in pieces, and the pieces left seams. This joins them
up, and fixes two things the reread turned up.

Deferred subsurface syncing is gone. `needs_tiles` existed because `select`
had no queue handle to sync with, so main.rs grew a bespoke event loop to
notice the flag afterwards. The dispatch handlers are handed a handle
already: pass it down and let `select` do the work itself. main.rs is back
to one uniform `pump`.

The layout is built once, in run(), and passed to App::new, rather than
built there and again inside it. `display` moves from Settings, which is
what App needs, to Options, which is what the caller needs it for.

`timeout = 0` meant an immediate deadline, so uncommenting the line in the
shipped config would have made wl-pick exit before you saw it. Zero now
means no timeout, which is what the comment beside it always claimed.

`timeout` was also settable but documented nowhere -- not in --help, not in
the README. Both now list every key config.rs accepts.

Theme::default's max-width/max-height were placeholder pixel counts that
happened to match one monitor. They are i32::MAX now: no cap of their own,
with Layout clamping to the display.

src/overlay.rs

@@ -236,30 +236,31 @@ impl App {
         surface.commit();
     }
 
-    fn move_sel(&mut self, delta: i32) {
+    fn move_sel(&mut self, delta: i32, qh: &QueueHandle<Self>) {
         let n = self.tiles.len() as i32;
         if n == 0 {
             return;
         }
-        self.select((self.sel as i32 + delta).rem_euclid(n) as usize);
+        self.select((self.sel as i32 + delta).rem_euclid(n) as usize, qh);
     }
 
-    fn move_row(&mut self, rows: i32) {
+    fn move_row(&mut self, rows: i32, qh: &QueueHandle<Self>) {
         let n = self.tiles.len() as i32;
         let target = self.sel as i32 + rows * self.layout.cols;
         if target >= 0 && target < n {
-            self.select(target as usize);
+            self.select(target as usize, qh);
         }
     }
 
     /// Move the selection, scrolling the least that keeps it on screen. Every
-    /// keyboard move goes through here, so the selection is never off-view.
-    fn select(&mut self, i: usize) {
+    /// move goes through here, so the selection is never off-view and the
+    /// subsurfaces always match the viewport.
+    fn select(&mut self, i: usize, qh: &QueueHandle<Self>) {
         self.sel = i;
         let scroll = self.layout.reveal(i, self.scroll);
         if scroll != self.scroll {
             self.scroll = scroll;
-            self.needs_tiles = true;
+            self.sync_tiles(qh);
         }
         self.paint();
     }
@@ -294,7 +295,7 @@ impl App {
         }
     }
 
-    fn key(&mut self, code: u32) {
+    fn key(&mut self, code: u32, qh: &QueueHandle<Self>) {
         match code {
             KEY_LEFTSHIFT | KEY_RIGHTSHIFT => self.shift = true,
             KEY_ESC | KEY_Q => self.ending = Ending::Cancelled,
@@ -302,15 +303,15 @@ impl App {
                 self.picked = self.tiles.get(self.sel).map(|t| t.target.clone());
                 self.ending = Ending::Picked;
             }
-            KEY_TAB if self.shift => self.move_sel(-1),
-            KEY_TAB | KEY_RIGHT | KEY_L => self.move_sel(1),
-            KEY_LEFT | KEY_H => self.move_sel(-1),
-            KEY_DOWN | KEY_J => self.move_row(1),
-            KEY_UP | KEY_K => self.move_row(-1),
-            KEY_HOME => self.select(0),
-            KEY_END => self.select(self.tiles.len().saturating_sub(1)),
-            KEY_PGUP => self.move_row(-self.layout.visible_rows),
-            KEY_PGDN => self.move_row(self.layout.visible_rows),
+            KEY_TAB if self.shift => self.move_sel(-1, qh),
+            KEY_TAB | KEY_RIGHT | KEY_L => self.move_sel(1, qh),
+            KEY_LEFT | KEY_H => self.move_sel(-1, qh),
+            KEY_DOWN | KEY_J => self.move_row(1, qh),
+            KEY_UP | KEY_K => self.move_row(-1, qh),
+            KEY_HOME => self.select(0, qh),
+            KEY_END => self.select(self.tiles.len().saturating_sub(1), qh),
+            KEY_PGUP => self.move_row(-self.layout.visible_rows, qh),
+            KEY_PGDN => self.move_row(self.layout.visible_rows, qh),
             _ => {}
         }
     }
@@ -373,11 +374,11 @@ impl Dispatch<WlKeyboard, ()> for App {
         event: wl_keyboard::Event,
         _: &(),
         _: &Connection,
-        _: &QueueHandle<Self>,
+        qh: &QueueHandle<Self>,
     ) {
         if let wl_keyboard::Event::Key { key, state, .. } = event {
             match state {
-                WEnum::Value(wl_keyboard::KeyState::Pressed) => app.key(key),
+                WEnum::Value(wl_keyboard::KeyState::Pressed) => app.key(key, qh),
                 WEnum::Value(wl_keyboard::KeyState::Released)
                     if key == KEY_LEFTSHIFT || key == KEY_RIGHTSHIFT =>
                 {
@@ -399,7 +400,7 @@ impl Dispatch<WlPointer, ()> for App {
         event: wl_pointer::Event,
         _: &(),
         _: &Connection,
-        _: &QueueHandle<Self>,
+        qh: &QueueHandle<Self>,
     ) {
         match event {
             wl_pointer::Event::Enter {
@@ -437,7 +438,9 @@ impl Dispatch<WlPointer, ()> for App {
                 state: WEnum::Value(state),
                 ..
             } => app.click(state == wl_pointer::ButtonState::Pressed),
-            wl_pointer::Event::Axis { value, .. } => app.move_sel(if value > 0.0 { 1 } else { -1 }),
+            wl_pointer::Event::Axis { value, .. } => {
+                app.move_sel(if value > 0.0 { 1 } else { -1 }, qh)
+            }
             _ => {}
         }
     }