refactor(ui): remove dead OS-window machinery after Plan B

With every dialog now an in-canvas modal, the per-dialog
`*_window: Option<window::Id>` fields are never set. Remove all 17
fields and their inits, trim `OsWindowClosed` to just the main window
(exit), drop the dialog branches from the window `title` closure, the
leftover `gain_focus` guards in the open handlers, and the now-unused
`iced::window` import in update.rs. Page-setup apply clears
`active_modal` instead of closing a window.

No behaviour change; native + web build, 75 tests pass.

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

src/app/mod.rs

@@ -277,33 +277,18 @@ pub(super) struct OpenCADStudio {
     /// Last point committed by a drawing command — used as ortho/polar base.
     last_point: Option<glam::Vec3>,
     /// OS window Id for the floating Layer Properties Manager (None when closed).
-    layer_window: Option<window::Id>,
     /// OS window Id of the primary application window.
     main_window: Option<window::Id>,
     // ── Floating panel windows ────────────────────────────────────────────
-    page_setup_window: Option<window::Id>,
-    textstyle_window: Option<window::Id>,
-    tablestyle_window: Option<window::Id>,
-    mlstyle_window: Option<window::Id>,
-    mleaderstyle_window: Option<window::Id>,
-    layout_manager_window: Option<window::Id>,
-    plotstyle_window: Option<window::Id>,
-    dimstyle_window: Option<window::Id>,
     /// Standalone "Select Color" palette window + the field it targets.
-    color_pick_window: Option<window::Id>,
     color_pick_target: Option<ColorPickTarget>,
-    shortcuts_window: Option<window::Id>,
-    about_window: Option<window::Id>,
     /// The open in-canvas modal dialog, if any (Plan B: shared overlay instead
     /// 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.
-    update_notice_window: Option<window::Id>,
     /// First-launch "make Open CAD Studio the default for .dwg/.dxf?" prompt
     /// window. Shown once, gated on `default_assoc_prompted`.
-    assoc_prompt_window: Option<window::Id>,
     /// Whether the one-time default-association prompt has already been shown.
     /// Persisted via [`settings::UserSettings`] so it survives restarts.
     default_assoc_prompted: bool,
@@ -334,7 +319,6 @@ pub(super) struct OpenCADStudio {
     last_vp_click_time: Option<Instant>,
     /// Screen position of the previous viewport left-click release.
     last_vp_click_pos: Option<Point>,
-    // page_setup_open: moved to page_setup_window: Option<window::Id>
     /// Editable paper width buffer for the Page Setup panel (string while typing).
     page_setup_w: String,
     /// Editable paper height buffer for the Page Setup panel (string while typing).
@@ -462,11 +446,9 @@ pub(super) struct OpenCADStudio {
     /// Set when the user tries to close a tab or quit while there are unsaved changes.
     pending_close: Option<PendingClose>,
     /// OS window for the unsaved-changes confirmation dialog.
-    unsaved_dialog_window: Option<window::Id>,
 
     // ── Custom Save-As dialog ─────────────────────────────────────────────
     /// OS window for the custom Save As dialog.
-    save_dialog_window: Option<window::Id>,
     /// Currently selected format string, e.g. "DWG 2013".
     save_dialog_format: String,
     /// Editable filename (without path), e.g. "drawing.dwg".
@@ -1429,24 +1411,9 @@ impl OpenCADStudio {
             show_file_tabs: true,
             show_layout_tabs: true,
             last_point: None,
-            layer_window: None,
             main_window: None,
-            page_setup_window: None,
-            textstyle_window: None,
-            tablestyle_window: None,
-            mlstyle_window: None,
-            mleaderstyle_window: None,
-            layout_manager_window: None,
-            plotstyle_window: None,
-            dimstyle_window: None,
-            color_pick_window: None,
             color_pick_target: None,
-            shortcuts_window: None,
-            about_window: None,
             active_modal: None,
-            plugin_manager_window: None,
-            update_notice_window: None,
-            assoc_prompt_window: None,
             default_assoc_prompted: false,
             update_notice_version: None,
             update_notice_body: None,
@@ -1469,8 +1436,6 @@ impl OpenCADStudio {
             page_setup_scale: "Fit".to_string(),
             opening: None,
             pending_close: None,
-            unsaved_dialog_window: None,
-            save_dialog_window: None,
             save_dialog_format: "DWG 2018".to_string(),
             save_dialog_filename: "drawing.dwg".to_string(),
             save_dialog_folder: std::env::var("HOME")
@@ -1722,57 +1687,7 @@ pub fn run() -> iced::Result {
     )
     .subscription(OpenCADStudio::subscription)
     .title(|state: &OpenCADStudio, window_id: window::Id| {
-        if Some(window_id) == state.layer_window {
+        let _ = window_id; // all dialogs are in-canvas modals now
-            return "Layer Properties Manager".into();
-        }
-        if Some(window_id) == state.color_pick_window {
-            return "Select Color".into();
-        }
-        if Some(window_id) == state.page_setup_window {
-            return "Page Setup".into();
-        }
-        if Some(window_id) == state.textstyle_window {
-            return "Text Style".into();
-        }
-        if Some(window_id) == state.tablestyle_window {
-            return "Table Style".into();
-        }
-        if Some(window_id) == state.mlstyle_window {
-            return "Multiline Style".into();
-        }
-        if Some(window_id) == state.mleaderstyle_window {
-            return "Multileader Style".into();
-        }
-        if Some(window_id) == state.layout_manager_window {
-            return "Layout Manager".into();
-        }
-        if Some(window_id) == state.plotstyle_window {
-            return "Plot Style Table Editor".into();
-        }
-        if Some(window_id) == state.dimstyle_window {
-            return "Dimension Style Manager".into();
-        }
-        if Some(window_id) == state.shortcuts_window {
-            return "Keyboard Shortcuts".into();
-        }
-        if Some(window_id) == state.about_window {
-            return "About Open CAD Studio".into();
-        }
-        if Some(window_id) == state.plugin_manager_window {
-            return "Plugin Manager".into();
-        }
-        if Some(window_id) == state.update_notice_window {
-            return "Update Available".into();
-        }
-        if Some(window_id) == state.assoc_prompt_window {
-            return "Set Default Application".into();
-        }
-        if Some(window_id) == state.unsaved_dialog_window {
-            return "Unsaved Changes".into();
-        }
-        if Some(window_id) == state.save_dialog_window {
-            return "Save As".into();
-        }
         if let Some(tab) = state.tabs.get(state.active_tab) {
             let dot = if tab.dirty { "● " } else { "" };
             let name = tab.tab_display_name();

src/app/update.rs

@@ -13,7 +13,6 @@ use crate::ui::PropertiesPanel;
 use acadrust::types::Color as AcadColor;
 use acadrust::{EntityType as AcadEntityType, Handle};
 use iced::time::Instant;
-use iced::window;
 use iced::{mouse, Task};
 
 const VIEWCUBE_HIT_SIZE: f32 = VIEWCUBE_DRAW_PX;
@@ -1665,101 +1664,11 @@ impl OpenCADStudio {
             }
 
             Message::OsWindowClosed(id) => {
+                // Only the main window exists now; all dialogs are in-canvas
+                // modals (Plan B). Closing it exits.
                 if self.main_window == Some(id) {
-                    // Main window was explicitly closed by us — exit.
                     return iced::exit();
                 }
-                if self.unsaved_dialog_window == Some(id) {
-                    // User closed the dialog window via OS ✕ — treat as Cancel.
-                    self.unsaved_dialog_window = None;
-                    self.pending_close = None;
-                    return Task::none();
-                }
-                if self.save_dialog_window == Some(id) {
-                    self.save_dialog_window = None;
-                    return Task::none();
-                }
-                // A style manager closed via OS ✕ counts as Cancel: discard any
-                // staged (not-yet-applied) changes by restoring the snapshot
-                // taken when it opened.
-                if self.textstyle_window == Some(id)
-                    || self.dimstyle_window == Some(id)
-                    || self.tablestyle_window == Some(id)
-                    || self.mleaderstyle_window == Some(id)
-                    || self.mlstyle_window == Some(id)
-                {
-                    self.style_stage_discard();
-                }
-                // Each popup window that's launched from a ribbon tool
-                // also turns that tool blue (`activate_tool`); when the
-                // window closes, the matching tool needs to be cleared
-                // or the button stays highlighted with no window behind
-                // it. The mapped IDs are the ribbon `ToolDef.id`s that
-                // dispatched the open in the first place. See #40.
-                if self.layer_window == Some(id) {
-                    self.layer_window = None;
-                    self.ribbon.deactivate_tool_if("LAYERS");
-                }
-                if self.page_setup_window == Some(id) {
-                    self.page_setup_window = None;
-                    self.ribbon.deactivate_tool_if("PAGESETUP");
-                }
-                if self.textstyle_window == Some(id) {
-                    self.textstyle_window = None;
-                    self.ribbon.deactivate_tool_if("STYLE");
-                    self.ribbon.deactivate_tool_if("TEXTSTYLE");
-                }
-                if self.tablestyle_window == Some(id) {
-                    self.tablestyle_window = None;
-                    self.ribbon.deactivate_tool_if("TABLESTYLE");
-                }
-                if self.mlstyle_window == Some(id) {
-                    self.mlstyle_window = None;
-                    self.ribbon.deactivate_tool_if("MLSTYLE");
-                }
-                if self.mleaderstyle_window == Some(id) {
-                    self.mleaderstyle_window = None;
-                    self.ribbon.deactivate_tool_if("MLEADERSTYLE");
-                }
-                if self.layout_manager_window == Some(id) {
-                    self.layout_manager_window = None;
-                    self.ribbon.deactivate_tool_if("LAYOUTMANAGER");
-                    self.ribbon.deactivate_tool_if("LAYOUTPANEL");
-                }
-                if self.plotstyle_window == Some(id) {
-                    self.plotstyle_window = None;
-                    self.ribbon.deactivate_tool_if("PLOTSTYLE");
-                    self.ribbon.deactivate_tool_if("STYLESMANAGER");
-                }
-                if self.dimstyle_window == Some(id) {
-                    self.dimstyle_window = None;
-                    self.ribbon.deactivate_tool_if("DIMSTYLE");
-                }
-                if self.color_pick_window == Some(id) {
-                    self.color_pick_window = None;
-                    self.color_pick_target = None;
-                }
-                if self.shortcuts_window == Some(id) {
-                    self.shortcuts_window = None;
-                    self.ribbon.deactivate_tool_if("SHORTCUTS");
-                    self.ribbon.deactivate_tool_if("KEYBOARD");
-                }
-                if self.about_window == Some(id) {
-                    self.about_window = None;
-                    self.ribbon.deactivate_tool_if("ABOUT");
-                }
-                if self.plugin_manager_window == Some(id) {
-                    self.plugin_manager_window = None;
-                }
-                if self.update_notice_window == Some(id) {
-                    self.update_notice_window = None;
-                }
-                // Closing the default-association prompt via the window chrome
-                // counts as answering it — never nag again.
-                if self.assoc_prompt_window == Some(id) {
-                    self.assoc_prompt_window = None;
-                    self.mark_assoc_prompted();
-                }
                 Task::none()
             }
 
@@ -5960,9 +5869,7 @@ impl OpenCADStudio {
                          center={center}  rot={rotation}°"
                     ));
                 }
-                if let Some(id) = self.page_setup_window.take() {
+                self.active_modal = None;
-                    return window::close(id);
-                }
                 Task::none()
             }
 
@@ -6522,9 +6429,6 @@ impl OpenCADStudio {
                     })
                     .unwrap_or_else(|| "Standard".to_string());
                 self.load_tablestyle_bufs(i);
-                if let Some(id) = self.tablestyle_window {
-                    return window::gain_focus(id);
-                }
                 self.active_modal = Some(super::ModalKind::TableStyle);
                 self.style_stage_begin();
                 Task::none()
@@ -6926,9 +6830,6 @@ impl OpenCADStudio {
                         .unwrap_or_else(|| "Standard".to_string())
                 };
                 self.load_mleaderstyle_bufs(i);
-                if let Some(id) = self.mleaderstyle_window {
-                    return window::gain_focus(id);
-                }
                 self.active_modal = Some(super::ModalKind::MLeaderStyle);
                 self.style_stage_begin();
                 Task::none()
@@ -7274,9 +7175,6 @@ impl OpenCADStudio {
                 };
                 self.dimstyle_selected = selected.clone();
                 self.load_dimstyle_bufs(i);
-                if let Some(id) = self.dimstyle_window {
-                    return window::gain_focus(id);
-                }
                 self.active_modal = Some(super::ModalKind::DimStyle);
                 self.style_stage_begin();
                 Task::none()
@@ -8513,9 +8411,6 @@ impl OpenCADStudio {
 
     /// Populate edit buffers from the currently selected text style.
     fn open_save_dialog_window(&mut self, tab_idx: usize) -> Task<Message> {
-        if let Some(id) = self.save_dialog_window {
-            return window::gain_focus(id);
-        }
         // Pre-fill filename and folder from current path or defaults.
         if let Some(p) = &self.tabs[tab_idx].current_path.clone() {
             if let Some(name) = p.file_name() {