fix: always open links in a new tab

This is a workaround for the app freezing because of
bfcache (see bevyengine/bevy#10328).

src/extra_egui.rs

@@ -0,0 +1,34 @@
+use bevy_egui::egui::{Link, Widget, WidgetText};
+
+/// Clickable hyperlink, same as [`bevy_egui::egui::Hyperlink`] but it always
+/// opens the url in a new tab.
+#[must_use = "You should put this widget in an ui with `ui.add(widget);`"]
+pub struct NewTabHyperlink {
+    url: &'static str,
+    text: WidgetText,
+}
+
+impl NewTabHyperlink {
+    pub fn from_label_and_url(text: impl Into<WidgetText>, url: &'static str) -> Self {
+        Self {
+            url,
+            text: text.into(),
+        }
+    }
+}
+impl Widget for NewTabHyperlink {
+    fn ui(self, ui: &mut bevy_egui::egui::Ui) -> bevy_egui::egui::Response {
+        let Self { url, text } = self;
+
+        let response = ui.add(Link::new(text));
+        if response.clicked() | response.middle_clicked() {
+            ui.ctx().output_mut(|o| {
+                o.open_url = Some(bevy_egui::egui::output::OpenUrl {
+                    url: url.to_string(),
+                    new_tab: true,
+                });
+            });
+        }
+        response.on_hover_text(url)
+    }
+}

src/gui.rs

@@ -2,6 +2,7 @@
 
 use crate::data::{Data, ReactionState};
 use crate::escher::{ArrowTag, EscherMap, Hover, MapState, NodeToText, ARROW_COLOR};
+use crate::extra_egui::NewTabHyperlink;
 use crate::geom::{AnyTag, Drag, HistTag, VisCondition, Xaxis};
 use crate::info::Info;
 use crate::screenshot::ScreenshotEvent;
@@ -317,7 +318,7 @@ pub fn ui_settings(
             }
         });
 
-        ui.add(egui::Hyperlink::from_label_and_url(
+        ui.add(NewTabHyperlink::from_label_and_url(
             "How to use?",
             "https://biosustain.github.io/shu/docs/plotting.html",
         ));

src/main.rs

@@ -9,6 +9,7 @@ use bevy_prototype_lyon::prelude::*;
 mod aesthetics;
 mod data;
 mod escher;
+mod extra_egui;
 mod funcplot;
 mod geom;
 mod gui;