feat(ui): unified modal dispatch; migrate 4 dialogs (Plan B)

Replace the per-dialog open flag with a single `active_modal:
Option<ModalKind>` and one `CloseModal` message. view_main matches it to
render the open dialog as an in-canvas modal.

Migrated off OS windows: About (content-sized), Shortcuts, Plugin
Manager and the Update notice (the latter three keep a bounded size via
a wrapping container, since their lists/scroll need defined bounds).

Native + web build; 75 tests pass.

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>

src/app/mod.rs

@@ -294,8 +294,9 @@ pub(super) struct OpenCADStudio {
     color_pick_target: Option<ColorPickTarget>,
     shortcuts_window: Option<window::Id>,
     about_window: Option<window::Id>,
-    /// In-canvas About modal (Plan B: shared overlay instead of an OS window).
+    /// The open in-canvas modal dialog, if any (Plan B: shared overlay instead
-    about_open: bool,
+    /// of OS windows).
+    active_modal: Option<ModalKind>,
     plugin_manager_window: Option<window::Id>,
     /// New-release notification window — opened on startup when the
     /// GitHub releases API reports a newer version than this build.
@@ -587,6 +588,17 @@ pub enum ColorPickTarget {
     Layer(usize),
 }
 
+/// Which in-canvas modal dialog is currently open (Plan B). At most one shows
+/// at a time; dialog-specific data lives in its own fields. Closed via the
+/// modal's ✕ (`Message::CloseModal`).
+#[derive(Clone, Copy, PartialEq, Eq)]
+pub enum ModalKind {
+    About,
+    Shortcuts,
+    PluginManager,
+    UpdateNotice,
+}
+
 /// Identifies a DimStyle field that can be edited in the dialog.
 #[derive(Debug, Clone, PartialEq, Eq)]
 pub enum DsField {
@@ -994,7 +1006,8 @@ pub enum Message {
     ShortcutsPanelClose,
     // ── About window ────────────────────────────────────────────────────
     AboutOpen,
-    AboutClose,
+    /// Close whatever in-canvas modal dialog is open (Plan B).
+    CloseModal,
     AboutCopyInfo,
     // ── Plugin Manager window ───────────────────────────────────────────
     PluginManagerOpen,
@@ -1416,7 +1429,7 @@ impl OpenCADStudio {
             color_pick_target: None,
             shortcuts_window: None,
             about_window: None,
-            about_open: false,
+            active_modal: None,
             plugin_manager_window: None,
             update_notice_window: None,
             assoc_prompt_window: None,

src/app/update.rs

@@ -5449,34 +5449,22 @@ impl OpenCADStudio {
 
             // ── Keyboard Shortcuts Panel ──────────────────────────────────────
             Message::ShortcutsPanelOpen => {
-                if let Some(id) = self.shortcuts_window {
+                self.active_modal = Some(super::ModalKind::Shortcuts);
-                    return window::gain_focus(id);
-                }
-                let (id, task) = window::open(window::Settings {
-                    size: iced::Size::new(720.0, 520.0),
-                    resizable: true,
-                    level: window::Level::AlwaysOnTop,
-                    ..Default::default()
-                });
-                self.shortcuts_window = Some(id);
-                task.map(|_| Message::Noop)
-            }
-            Message::ShortcutsPanelClose => {
-                if let Some(id) = self.shortcuts_window.take() {
-                    window::close(id)
-                } else {
                 Task::none()
             }
+            Message::ShortcutsPanelClose => {
+                self.active_modal = None;
+                Task::none()
             }
 
             // ── About window ──────────────────────────────────────────────
             Message::AboutOpen => {
-                self.about_open = true;
+                self.active_modal = Some(super::ModalKind::About);
                 Task::none()
             }
 
-            Message::AboutClose => {
+            Message::CloseModal => {
-                self.about_open = false;
+                self.active_modal = None;
                 Task::none()
             }
 
@@ -5492,24 +5480,12 @@ impl OpenCADStudio {
 
             // ── Plugin Manager window ─────────────────────────────────────
             Message::PluginManagerOpen => {
-                if let Some(id) = self.plugin_manager_window {
+                self.active_modal = Some(super::ModalKind::PluginManager);
-                    return window::gain_focus(id);
-                }
-                let (id, task) = window::open(window::Settings {
-                    size: iced::Size::new(520.0, 460.0),
-                    resizable: true,
-                    level: window::Level::AlwaysOnTop,
-                    ..Default::default()
-                });
-                self.plugin_manager_window = Some(id);
-                task.map(|_| Message::Noop)
-            }
-            Message::PluginManagerClose => {
-                if let Some(id) = self.plugin_manager_window.take() {
-                    window::close(id)
-                } else {
                 Task::none()
             }
+            Message::PluginManagerClose => {
+                self.active_modal = None;
+                Task::none()
             }
 
             Message::EnterViewport(handle) => {
@@ -5788,36 +5764,18 @@ impl OpenCADStudio {
                 };
                 self.update_notice_version = Some(info.version);
                 self.update_notice_body = Some(info.body);
-                if let Some(id) = self.update_notice_window {
+                self.active_modal = Some(super::ModalKind::UpdateNotice);
-                    return window::gain_focus(id);
-                }
-                let (id, task) = window::open(window::Settings {
-                    // Sized for the new release-notes panel — wide enough
-                    // for typical GitHub release headlines, tall enough for
-                    // a meaningful scroll preview without dwarfing the app.
-                    size: iced::Size::new(560.0, 460.0),
-                    resizable: true,
-                    level: window::Level::AlwaysOnTop,
-                    ..Default::default()
-                });
-                self.update_notice_window = Some(id);
-                task.map(|_| Message::Noop)
-            }
-            Message::UpdateNoticeClose => {
-                if let Some(id) = self.update_notice_window.take() {
-                    window::close(id)
-                } else {
                 Task::none()
             }
+            Message::UpdateNoticeClose => {
+                self.active_modal = None;
+                Task::none()
             }
             Message::UpdateNoticeOpenRelease => {
                 crate::sys::open_url(crate::update_check::RELEASES_PAGE);
-                if let Some(id) = self.update_notice_window.take() {
+                self.active_modal = None;
-                    window::close(id)
-                } else {
                 Task::none()
             }
-            }
             Message::AssocPromptYes => {
                 self.mark_assoc_prompted();
                 let close = if let Some(id) = self.assoc_prompt_window.take() {

src/app/view.rs

@@ -1517,14 +1517,43 @@ impl OpenCADStudio {
         // ── In-canvas modal dialogs (Plan B) ───────────────────────────────
         // Former pop-up windows render as overlays here, so they work on both
         // the native (single main window) and web builds.
-        if self.about_open {
+        use crate::ui::modal::modal;
-            crate::ui::modal::modal(
+        match self.active_modal {
+            Some(super::ModalKind::About) => {
+                modal(composed, crate::ui::about::view_window(), Message::CloseModal)
+            }
+            Some(super::ModalKind::Shortcuts) => modal(
                 composed,
-                crate::ui::about::view_window(),
+                // Content-heavy dialogs (lists / scroll) keep a bounded size —
-                Message::AboutClose,
+                // their inner `Fill` widgets fill it — instead of shrinking.
+                iced::widget::container(crate::ui::shortcuts::view_window(
+                    &self.shortcut_overrides,
+                ))
+                .width(720)
+                .height(520),
+                Message::CloseModal,
+            ),
+            Some(super::ModalKind::PluginManager) => modal(
+                composed,
+                iced::widget::container(crate::ui::plugin_manager::view_window(
+                    &crate::plugin::installed_manifests(),
+                ))
+                .width(520)
+                .height(460),
+                Message::CloseModal,
+            ),
+            Some(super::ModalKind::UpdateNotice) => {
+                let latest = self.update_notice_version.as_deref().unwrap_or("?");
+                let body = self.update_notice_body.as_deref().unwrap_or("");
+                modal(
+                    composed,
+                    iced::widget::container(crate::ui::update_notice::view_window(latest, body))
+                        .width(560)
+                        .height(460),
+                    Message::CloseModal,
                 )
-        } else {
+            }
-            composed.into()
+            None => composed.into(),
         }
     }