fix(zbugs-rune): open an issue at once, without fading (#185)

Selecting an issue faded the last one's text out while the new one's faded
in, and the list's highlight crossfaded beside it, for about 0.4 s: every
Rune element fades in and out by default, and a press or key animates its
commit. The issue pane now lands its changes at once
(`El::instant_changes`), the highlight moves in the same frame, and the
last issue stays until the next one's rows come, a frame later from the
local store, rather than a frame of "Loading…" between. As zbugs-swift and
zbugs-gpui do.

Amp-Thread-ID: https://ampcode.com/threads/T-b98159d5-62b9-4743-85ee-2b18907aaa6a

Co-authored-by: Amp <amp@ampcode.com>

Author: tmm

apps/zbugs-rune/src/main.rs

@@ -538,11 +538,10 @@ impl App {
         if self.selected.as_ref() == Some(&id) {
             return;
         }
-        self.detail = None;
-        self.detail_result = ResultType::Unknown;
+        // The last issue and its comments stay until this one's rows come,
+        // a frame later from the local store, rather than "Loading…" between.
         self.picker = None;
         self.editing_comment = None;
-        self.comments.clear();
         self.comments_limit = COMMENTS_PAGE;
         self.comment = TextEdit::new("");
         self.watch_detail(&id);
@@ -687,6 +686,7 @@ impl App {
         };
         let id = issue.id.clone();
         tx.scroll_into_view(id.clone());
+        tx.color_motion(rune::Spring::NONE);
         self.select(id);
         // Near the end of what's loaded: the next page.
         if let Some(i) = to {

apps/zbugs-rune/src/view.rs

@@ -701,7 +701,11 @@ fn issue_row(s: &App, issue: &Issue, k: &Kit) -> El {
         .w_full()
         .px(12.0)
         .py(9.0)
-        .on_press(move |s: &mut App| s.select(id.clone()))
+        .on_press_tx(move |s: &mut App, tx| {
+            // The highlight moves at once, with the issue beside it.
+            tx.color_motion(rune::Spring::NONE);
+            s.select(id.clone());
+        })
         .child(text_col.w_full());
     if selected {
         r = r.fill(k.c.layer_02);
@@ -795,8 +799,11 @@ fn detail(s: &App, k: &Kit, layer: &mut Vec<El>) -> El {
             .build(k)
             .key("search"),
     );
+    // Another issue lands at once, as in zbugs-swift and zbugs-gpui: without
+    // this, Rune fades the last issue's text out while the new one fades in.
     let frame = col()
         .key("detail")
+        .instant_changes()
         .grow(1.0)
         .h_full()
         .min_w(0.0)