feat(styles): make style managers transactional — persist only on Apply

A style manager is now a staged transaction. When it opens, a snapshot of
the style tables, style objects and current-style pointers is taken. Every
New / Copy / Delete / Rename / Set Current / property edit mutates the
document live so the dialog previews the result, but the tab is not marked
dirty, nothing is pushed to undo, and the drawing is not rebuilt.

- Apply commits: one undo entry (restoring the pre-edit state), the tab is
  marked dirty, the drawing rebuilds, and the baseline is reset so further
  edits stage afresh.
- Closing the window without Apply discards: the opening snapshot is
  restored, so none of the changes persist.

Side effects (dirty / undo / bump_geometry) were removed from every style
edit handler and routed exclusively through the commit. Multiline's Apply
is a structural-only commit since its editor has no editable properties.

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

src/app/mod.rs

@@ -391,6 +391,10 @@ pub(super) struct OpenCADStudio {
     style_rename: Option<String>,
     /// Edit buffer for the inline rename text input.
     style_rename_buf: String,
+    /// Active style-manager transaction. Edits mutate the document live for an
+    /// in-dialog preview but only persist on Apply; closing without Apply
+    /// restores this snapshot. `None` when no style manager is staging.
+    style_stage: Option<style_ops::StyleStage>,
 
     // ── TextStyle Font Browser ────────────────────────────────────────────
     textstyle_selected: String,
@@ -1390,6 +1394,7 @@ impl OpenCADStudio {
             // TextStyle font browser
             style_rename: None,
             style_rename_buf: String::new(),
+            style_stage: None,
             textstyle_selected: "Standard".to_string(),
             textstyle_font: String::new(),
             textstyle_width: "1.0".to_string(),

src/app/style_ops.rs

@@ -341,15 +341,19 @@ impl OpenCADStudio {
 
     // ── Public operations (called by the message handlers) ─────────────────
 
+    // Note: the structural ops below mutate the document live (so the dialog
+    // shows a preview) but do NOT mark the tab dirty, push undo, or rebuild the
+    // drawing. Those side effects are deferred to `style_stage_commit` (Apply);
+    // closing the window without Apply calls `style_stage_discard`, which
+    // restores the snapshot taken when the manager opened.
+
     pub(super) fn style_new(&mut self, kind: StyleKind) {
         let i = self.active_tab;
         let name = self.unique_new_name(kind);
-        self.push_undo_snapshot(i, "STYLE NEW");
         let h = self.tabs[i].scene.document.allocate_handle();
         self.insert_default_style(kind, &name, h);
         self.set_style_selected(kind, name.clone());
         self.load_style_bufs(kind);
-        self.tabs[i].dirty = true;
         self.after_style_change(kind);
         self.command_line
             .push_output(&format!("Style '{name}' created."));
@@ -359,28 +363,24 @@ impl OpenCADStudio {
         let i = self.active_tab;
         let src = self.style_selected(kind);
         let name = self.unique_suffixed_name(kind, &src);
-        self.push_undo_snapshot(i, "STYLE COPY");
         let h = self.tabs[i].scene.document.allocate_handle();
         if !self.clone_style_as(kind, &src, &name, h) {
             return;
         }
         self.set_style_selected(kind, name.clone());
         self.load_style_bufs(kind);
-        self.tabs[i].dirty = true;
         self.after_style_change(kind);
         self.command_line
             .push_output(&format!("Style '{name}' created."));
     }
 
     pub(super) fn style_delete(&mut self, kind: StyleKind) {
-        let i = self.active_tab;
         let name = self.style_selected(kind);
         if name.eq_ignore_ascii_case("Standard") {
             self.command_line
                 .push_error("Cannot delete the Standard style.");
             return;
         }
-        self.push_undo_snapshot(i, "STYLE DEL");
         if !self.remove_style_storage(kind, &name) {
             return;
         }
@@ -391,7 +391,6 @@ impl OpenCADStudio {
             .unwrap_or_else(|| "Standard".to_string());
         self.set_style_selected(kind, first);
         self.load_style_bufs(kind);
-        self.tabs[i].dirty = true;
         self.after_style_change(kind);
         self.command_line
             .push_output(&format!("Style '{name}' deleted."));
@@ -408,7 +407,6 @@ impl OpenCADStudio {
     /// Commit the inline rename. No-op (with feedback) on empty / unchanged /
     /// colliding names, and the Standard style cannot be renamed.
     pub(super) fn style_rename_commit(&mut self, kind: StyleKind) {
-        let i = self.active_tab;
         let Some(old) = self.style_rename.take() else {
             return;
         };
@@ -427,13 +425,11 @@ impl OpenCADStudio {
                 .push_error(&format!("Style '{new}' already exists."));
             return;
         }
-        self.push_undo_snapshot(i, "STYLE RENAME");
         self.rename_style_storage(kind, &old, &new);
         if self.style_selected(kind).eq_ignore_ascii_case(&old) {
             self.set_style_selected(kind, new.clone());
         }
         self.load_style_bufs(kind);
-        self.tabs[i].dirty = true;
         self.after_style_change(kind);
         self.command_line
             .push_output(&format!("Renamed '{old}' → '{new}'."));
@@ -443,6 +439,139 @@ impl OpenCADStudio {
         self.style_rename = None;
         self.style_rename_buf.clear();
     }
+
+    // ── Staging: nothing persists until Apply ──────────────────────────────
+    //
+    // A style manager is a transaction. When it opens we snapshot the style
+    // tables / objects / current pointers; every New / Copy / Delete / Rename /
+    // Set Current / property edit mutates the live document for an in-dialog
+    // preview, but the tab stays clean and the drawing is not rebuilt. Apply
+    // commits (marks dirty, pushes one undo entry, rebuilds); closing the
+    // window without Apply discards by restoring the snapshot.
+
+    /// Snapshot the style-related document state into a transferable record.
+    fn capture_style_state(&self) -> StyleStateSnapshot {
+        let i = self.active_tab;
+        let doc = &self.tabs[i].scene.document;
+        let style_objects = doc
+            .objects
+            .iter()
+            .filter(|(_, o)| {
+                matches!(
+                    o,
+                    ObjectType::TableStyle(_)
+                        | ObjectType::MLineStyle(_)
+                        | ObjectType::MultiLeaderStyle(_)
+                )
+            })
+            .map(|(&h, o)| (h, o.clone()))
+            .collect();
+        StyleStateSnapshot {
+            text_styles: doc.text_styles.clone(),
+            dim_styles: doc.dim_styles.clone(),
+            style_objects,
+            current_text: doc.header.current_text_style_name.clone(),
+            current_dim: doc.header.current_dimstyle_name.clone(),
+            multiline_style: doc.header.multiline_style.clone(),
+            active_table: self.ribbon.active_table_style.clone(),
+            active_mleader: self.ribbon.active_mleader_style.clone(),
+            tab_active_mleader: self.tabs[i].active_mleader_style.clone(),
+        }
+    }
+
+    /// Overwrite the live style state with a snapshot (used by commit's undo
+    /// dance and by discard).
+    fn restore_style_state(&mut self, snap: &StyleStateSnapshot) {
+        let i = self.active_tab;
+        let doc = &mut self.tabs[i].scene.document;
+        doc.text_styles = snap.text_styles.clone();
+        doc.dim_styles = snap.dim_styles.clone();
+        doc.objects.retain(|_, o| {
+            !matches!(
+                o,
+                ObjectType::TableStyle(_)
+                    | ObjectType::MLineStyle(_)
+                    | ObjectType::MultiLeaderStyle(_)
+            )
+        });
+        for (h, o) in &snap.style_objects {
+            doc.objects.insert(*h, o.clone());
+        }
+        doc.header.current_text_style_name = snap.current_text.clone();
+        doc.header.current_dimstyle_name = snap.current_dim.clone();
+        doc.header.multiline_style = snap.multiline_style.clone();
+        self.ribbon.active_table_style = snap.active_table.clone();
+        self.ribbon.active_mleader_style = snap.active_mleader.clone();
+        self.tabs[i].active_mleader_style = snap.tab_active_mleader.clone();
+    }
+
+    /// Begin a staging transaction for a freshly-opened style manager.
+    pub(super) fn style_stage_begin(&mut self) {
+        let dirty_at_open = self.tabs[self.active_tab].dirty;
+        let baseline = self.capture_style_state();
+        self.style_stage = Some(StyleStage {
+            dirty_at_open,
+            baseline,
+        });
+    }
+
+    /// Commit the staged changes (Apply): make them permanent with a single
+    /// undo entry, mark the tab dirty, and rebuild the drawing.
+    pub(super) fn style_stage_commit(&mut self) {
+        let i = self.active_tab;
+        let Some(stage) = self.style_stage.take() else {
+            // No active transaction — still refresh the drawing so a bare Apply
+            // is harmless.
+            self.tabs[i].dirty = true;
+            self.tabs[i].scene.bump_geometry();
+            self.sync_ribbon_styles();
+            return;
+        };
+        // Capture the edited state, rewind to the baseline so the undo entry
+        // restores the pre-edit document, then re-apply the edits on top.
+        let edited = self.capture_style_state();
+        self.restore_style_state(&stage.baseline);
+        self.push_undo_snapshot(i, "STYLE");
+        self.restore_style_state(&edited);
+        self.tabs[i].dirty = true;
+        self.tabs[i].scene.bump_geometry();
+        self.sync_ribbon_styles();
+        // Re-baseline so further edits in the still-open window stage afresh.
+        self.style_stage = Some(StyleStage {
+            dirty_at_open: true,
+            baseline: edited,
+        });
+    }
+
+    /// Discard staged changes (window closed without Apply): restore the
+    /// snapshot taken when the manager opened.
+    pub(super) fn style_stage_discard(&mut self) {
+        let Some(stage) = self.style_stage.take() else {
+            return;
+        };
+        self.restore_style_state(&stage.baseline);
+        self.tabs[self.active_tab].dirty = stage.dirty_at_open;
+        self.sync_ribbon_styles();
+    }
+}
+
+/// Snapshot of every document field a style manager can touch.
+pub(super) struct StyleStateSnapshot {
+    text_styles: acadrust::tables::Table<TextStyle>,
+    dim_styles: acadrust::tables::Table<DimStyle>,
+    style_objects: Vec<(Handle, ObjectType)>,
+    current_text: String,
+    current_dim: String,
+    multiline_style: String,
+    active_table: String,
+    active_mleader: String,
+    tab_active_mleader: String,
+}
+
+/// An in-progress style-manager transaction.
+pub(super) struct StyleStage {
+    dirty_at_open: bool,
+    baseline: StyleStateSnapshot,
 }
 
 // ── Object-store helpers ───────────────────────────────────────────────────

src/app/update.rs

@@ -1519,6 +1519,17 @@ impl OpenCADStudio {
                     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
@@ -6127,6 +6138,7 @@ impl OpenCADStudio {
                     ..Default::default()
                 });
                 self.textstyle_window = Some(id);
+                self.style_stage_begin();
                 task.map(|_| Message::Noop)
             }
             Message::TextStyleDialogClose => {
@@ -6143,12 +6155,11 @@ impl OpenCADStudio {
                 Task::none()
             }
             Message::TextStyleDialogSetCurrent => {
+                // Staged: persists on Apply.
                 let i = self.active_tab;
                 let name = self.textstyle_selected.clone();
                 if self.tabs[i].scene.document.text_styles.get(&name).is_some() {
-                    self.push_undo_snapshot(i, "STYLE SET");
                     self.tabs[i].scene.document.header.current_text_style_name = name.clone();
-                    self.tabs[i].dirty = true;
                     self.sync_ribbon_styles();
                     self.command_line
                         .push_output(&format!("Current text style: {}", name));
@@ -6199,63 +6210,52 @@ impl OpenCADStudio {
                 Task::none()
             }
             Message::TextStyleToggle(field) => {
+                // Staged: mutate live for preview, persist on Apply.
                 let i = self.active_tab;
                 let name = self.textstyle_selected.clone();
-                if self.tabs[i].scene.document.text_styles.get(&name).is_some() {
+                if let Some(s) = self.tabs[i].scene.document.text_styles.get_mut(&name) {
-                    self.push_undo_snapshot(i, "STYLE EDIT");
+                    match field {
-                    if let Some(s) = self.tabs[i].scene.document.text_styles.get_mut(&name) {
+                        "backward" => s.flags.backward = !s.flags.backward,
-                        match field {
+                        "upside_down" => s.flags.upside_down = !s.flags.upside_down,
-                            "backward" => s.flags.backward = !s.flags.backward,
+                        "annotative" => s.annotative = !s.annotative,
-                            "upside_down" => s.flags.upside_down = !s.flags.upside_down,
+                        _ => {}
-                            "annotative" => s.annotative = !s.annotative,
-                            _ => {}
-                        }
                     }
-                    self.tabs[i].scene.bump_geometry();
-                    self.tabs[i].dirty = true;
                 }
                 Task::none()
             }
             Message::TextStyleApply => {
                 let i = self.active_tab;
                 let name = self.textstyle_selected.clone();
-                if self.tabs[i].scene.document.text_styles.get(&name).is_some() {
+                let font = self.textstyle_font.clone();
-                    self.push_undo_snapshot(i, "STYLE EDIT");
+                let width_str = self.textstyle_width.clone();
-                    let font = self.textstyle_font.clone();
+                let oblique_str = self.textstyle_oblique.clone();
-                    let width_str = self.textstyle_width.clone();
+                let height_str = self.textstyle_height.clone();
-                    let oblique_str = self.textstyle_oblique.clone();
+                let bigfont = self.textstyle_bigfont.clone();
-                    let height_str = self.textstyle_height.clone();
+                let ttf = self.textstyle_ttf.clone();
-                    let bigfont = self.textstyle_bigfont.clone();
+                if let Some(s) = self.tabs[i].scene.document.text_styles.get_mut(&name) {
-                    let ttf = self.textstyle_ttf.clone();
+                    s.font_file = font;
-                    if let Some(s) = self.tabs[i].scene.document.text_styles.get_mut(&name) {
+                    s.big_font_file = bigfont;
-                        s.font_file = font;
+                    s.true_type_font = ttf;
-                        s.big_font_file = bigfont;
+                    if let Ok(w) = width_str.trim().parse::<f64>() {
-                        s.true_type_font = ttf;
+                        s.width_factor = w;
-                        if let Ok(w) = width_str.trim().parse::<f64>() {
+                    }
-                            s.width_factor = w;
+                    if let Ok(a) = oblique_str.trim().parse::<f64>() {
-                        }
+                        s.oblique_angle = a.to_radians();
-                        if let Ok(a) = oblique_str.trim().parse::<f64>() {
+                    }
-                            s.oblique_angle = a.to_radians();
+                    if let Ok(h) = height_str.trim().parse::<f64>() {
-                        }
+                        s.height = h.max(0.0);
-                        if let Ok(h) = height_str.trim().parse::<f64>() {
-                            s.height = h.max(0.0);
-                        }
                     }
-                    self.tabs[i].scene.bump_geometry();
-                    self.tabs[i].dirty = true;
                 }
+                self.style_stage_commit();
                 Task::none()
             }
             Message::TextStyleFontPick(font_file) => {
+                // Staged: update the buffer + live style; persist on Apply.
                 let i = self.active_tab;
                 self.textstyle_font = font_file.clone();
                 let name = self.textstyle_selected.clone();
-                if self.tabs[i].scene.document.text_styles.get(&name).is_some() {
+                if let Some(s) = self.tabs[i].scene.document.text_styles.get_mut(&name) {
-                    self.push_undo_snapshot(i, "STYLE FONT");
+                    s.font_file = font_file;
-                    if let Some(s) = self.tabs[i].scene.document.text_styles.get_mut(&name) {
-                        s.font_file = font_file;
-                    }
-                    self.tabs[i].dirty = true;
                 }
                 Task::none()
             }
@@ -6288,6 +6288,7 @@ impl OpenCADStudio {
                     ..Default::default()
                 });
                 self.tablestyle_window = Some(id);
+                self.style_stage_begin();
                 task.map(|_| Message::Noop)
             }
             Message::TableStyleDialogClose => {
@@ -6321,7 +6322,6 @@ impl OpenCADStudio {
                 let h: Option<f64> = self.ts_hmargin.trim().parse().ok();
                 let v: Option<f64> = self.ts_vmargin.trim().parse().ok();
                 let desc = self.ts_description.clone();
-                self.push_undo_snapshot(i, "TABLESTYLE EDIT");
                 for obj in self.tabs[i].scene.document.objects.values_mut() {
                     if let ObjectType::TableStyle(s) = obj {
                         if s.name == name {
@@ -6335,7 +6335,7 @@ impl OpenCADStudio {
                         }
                     }
                 }
-                self.tabs[i].dirty = true;
+                self.style_stage_commit();
                 Task::none()
             }
 
@@ -6347,8 +6347,6 @@ impl OpenCADStudio {
                         "Up" => TableFlowDirection::Up,
                         _ => TableFlowDirection::Down,
                     };
-                    self.push_undo_snapshot(i, "TABLESTYLE EDIT");
-                    self.tabs[i].dirty = true;
                 }
                 Task::none()
             }
@@ -6404,9 +6402,6 @@ impl OpenCADStudio {
                             _ => TableBorderType::Single,
                         };
                     }
-                    self.push_undo_snapshot(i, "TABLESTYLE EDIT");
-                    self.tabs[i].dirty = true;
-                    self.tabs[i].scene.bump_geometry();
                 }
                 Task::none()
             }
@@ -6419,9 +6414,6 @@ impl OpenCADStudio {
                     {
                         bd.is_invisible = !bd.is_invisible;
                     }
-                    self.push_undo_snapshot(i, "TABLESTYLE EDIT");
-                    self.tabs[i].dirty = true;
-                    self.tabs[i].scene.bump_geometry();
                 }
                 Task::none()
             }
@@ -6432,9 +6424,6 @@ impl OpenCADStudio {
                     if let Some(c) = Self::ts_cell_of(s, row) {
                         c.fill_enabled = !c.fill_enabled;
                     }
-                    self.push_undo_snapshot(i, "TABLESTYLE EDIT");
-                    self.tabs[i].dirty = true;
-                    self.tabs[i].scene.bump_geometry();
                 }
                 Task::none()
             }
@@ -6456,9 +6445,6 @@ impl OpenCADStudio {
                             _ => CellAlignment::MiddleCenter,
                         };
                     }
-                    self.push_undo_snapshot(i, "TABLESTYLE EDIT");
-                    self.tabs[i].dirty = true;
-                    self.tabs[i].scene.bump_geometry();
                 }
                 Task::none()
             }
@@ -6521,9 +6507,6 @@ impl OpenCADStudio {
                             }
                         }
                     }
-                    self.push_undo_snapshot(i, "TABLESTYLE EDIT");
-                    self.tabs[i].dirty = true;
-                    self.tabs[i].scene.bump_geometry();
                 }
                 Task::none()
             }
@@ -6532,7 +6515,6 @@ impl OpenCADStudio {
                 use acadrust::objects::ObjectType;
                 let i = self.active_tab;
                 let name = self.tablestyle_selected.clone();
-                self.push_undo_snapshot(i, "TABLESTYLE EDIT");
                 for obj in self.tabs[i].scene.document.objects.values_mut() {
                     if let ObjectType::TableStyle(s) = obj {
                         if s.name == name {
@@ -6544,7 +6526,6 @@ impl OpenCADStudio {
                         }
                     }
                 }
-                self.tabs[i].dirty = true;
                 Task::none()
             }
 
@@ -6552,7 +6533,6 @@ impl OpenCADStudio {
                 use acadrust::objects::ObjectType;
                 let i = self.active_tab;
                 let name = self.tablestyle_selected.clone();
-                self.push_undo_snapshot(i, "TABLESTYLE EDIT");
                 for obj in self.tabs[i].scene.document.objects.values_mut() {
                     if let ObjectType::TableStyle(s) = obj {
                         if s.name == name {
@@ -6560,7 +6540,6 @@ impl OpenCADStudio {
                         }
                     }
                 }
-                self.tabs[i].dirty = true;
                 Task::none()
             }
 
@@ -6627,6 +6606,7 @@ impl OpenCADStudio {
                     ..Default::default()
                 });
                 self.mlstyle_window = Some(id);
+                self.style_stage_begin();
                 task.map(|_| Message::Noop)
             }
             Message::MlStyleDialogClose => {
@@ -6651,9 +6631,8 @@ impl OpenCADStudio {
                     .values()
                     .any(|o| matches!(o, ObjectType::MLineStyle(s) if s.name == name));
                 if exists {
-                    self.push_undo_snapshot(i, "MLSTYLE SET");
+                    // Staged: persists on Apply.
                     self.tabs[i].scene.document.header.multiline_style = name.clone();
-                    self.tabs[i].dirty = true;
                     self.command_line
                         .push_output(&format!("Current multiline style: {}", name));
                 }
@@ -6663,7 +6642,12 @@ impl OpenCADStudio {
             // Apply pair as every other style manager. The editor is currently
             // read-only, so there is nothing to apply yet — wire this up when
             // editable MLineStyle properties land.
-            Message::MlStyleApply => Task::none(),
+            Message::MlStyleApply => {
+                // Multiline styles have no editable properties yet; Apply still
+                // commits any staged structural / current-style changes.
+                self.style_stage_commit();
+                Task::none()
+            }
             Message::MlStyleDialogNew => {
                 self.style_new(crate::app::StyleKind::MLine);
                 Task::none()
@@ -6716,6 +6700,7 @@ impl OpenCADStudio {
                     ..Default::default()
                 });
                 self.mleaderstyle_window = Some(id);
+                self.style_stage_begin();
                 task.map(|_| Message::Noop)
             }
             Message::MLeaderStyleDialogClose => {
@@ -6802,9 +6787,6 @@ impl OpenCADStudio {
                         }
                         _ => {}
                     }
-                    self.push_undo_snapshot(i, "MLEADERSTYLE EDIT");
-                    self.tabs[i].dirty = true;
-                    self.tabs[i].scene.bump_geometry();
                 }
                 Task::none()
             }
@@ -6900,9 +6882,6 @@ impl OpenCADStudio {
                         }
                         _ => {}
                     }
-                    self.push_undo_snapshot(i, "MLEADERSTYLE EDIT");
-                    self.tabs[i].dirty = true;
-                    self.tabs[i].scene.bump_geometry();
                 }
                 Task::none()
             }
@@ -6939,9 +6918,6 @@ impl OpenCADStudio {
                         "block_content_handle" => s.block_content_handle = handle,
                         _ => {}
                     }
-                    self.push_undo_snapshot(i, "MLEADERSTYLE EDIT");
-                    self.tabs[i].dirty = true;
-                    self.tabs[i].scene.bump_geometry();
                 }
                 Task::none()
             }
@@ -7026,10 +7002,8 @@ impl OpenCADStudio {
                     if let Some(v) = bsz {
                         s.block_content_scale_z = v;
                     }
-                    self.push_undo_snapshot(i, "MLEADERSTYLE EDIT");
-                    self.tabs[i].dirty = true;
-                    self.tabs[i].scene.bump_geometry();
                 }
+                self.style_stage_commit();
                 Task::none()
             }
 
@@ -7067,6 +7041,7 @@ impl OpenCADStudio {
                     ..Default::default()
                 });
                 self.dimstyle_window = Some(id);
+                self.style_stage_begin();
                 task.map(|_| Message::Noop)
             }
             Message::DimStyleDialogClose => {
@@ -7079,6 +7054,7 @@ impl OpenCADStudio {
             Message::DimStyleDialogApply => {
                 let i = self.active_tab;
                 self.apply_dimstyle_bufs(i);
+                self.style_stage_commit();
                 Task::none()
             }
             Message::DimStyleDialogSelect(name) => {
@@ -7100,11 +7076,10 @@ impl OpenCADStudio {
                 Task::none()
             }
             Message::DimStyleDialogSetCurrent => {
+                // Staged: persists on Apply.
                 let i = self.active_tab;
-                self.push_undo_snapshot(i, "DIMSTYLE SETCURRENT");
                 self.tabs[i].scene.document.header.current_dimstyle_name =
                     self.dimstyle_selected.clone();
-                self.tabs[i].dirty = true;
                 self.sync_ribbon_styles();
                 self.command_line.push_output(&format!(
                     "Current dim style set to '{}'.",
@@ -7147,7 +7122,7 @@ impl OpenCADStudio {
                         .map(|b| b.handle)
                         .unwrap_or(acadrust::types::Handle::NULL)
                 };
-                self.push_undo_snapshot(i, "DIMSTYLE EDIT");
+                // Staged: persists on Apply.
                 if let Some(ds) = self.tabs[i].scene.document.dim_styles.get_mut(&name) {
                     match field {
                         "dimblk" => ds.dimblk = handle,
@@ -7160,8 +7135,6 @@ impl OpenCADStudio {
                         _ => {}
                     }
                 }
-                self.tabs[i].dirty = true;
-                self.tabs[i].scene.bump_geometry();
                 Task::none()
             }
         }
@@ -7888,7 +7861,6 @@ impl OpenCADStudio {
 
     /// Write edit buffers back into the selected dim style document entry.
     fn apply_dimstyle_bufs(&mut self, tab: usize) {
-        self.push_undo_snapshot(tab, "DIMSTYLE EDIT");
         let doc = &mut self.tabs[tab].scene.document;
         let Some(ds) = doc.dim_styles.get_mut(&self.dimstyle_selected) else {
             return;
@@ -7979,7 +7951,6 @@ impl OpenCADStudio {
         ds.dimtofl = self.ds_dimtofl;
         ds.dimalt = self.ds_dimalt;
         ds.dimapost = self.ds_dimapost.clone();
-        self.tabs[tab].dirty = true;
         self.command_line
             .push_output(&format!("DimStyle '{}' updated.", self.dimstyle_selected));
     }

src/ui/mleaderstyle.rs

@@ -2,7 +2,7 @@
 
 use crate::app::Message;
 use iced::widget::{
-    button, checkbox, column, container, pick_list, row, scrollable, text, text_input, Space,
+    button, checkbox, column, container, pick_list, row, scrollable, text, text_input,
 };
 use iced::{Background, Border, Color, Element, Fill, Theme};
 

src/ui/mlstyle.rs

@@ -1,8 +1,8 @@
 //! Multiline Style Manager window — fills the entire OS window.
 
 use crate::app::Message;
-use iced::widget::{column, container, row, scrollable, text, Space};
+use iced::widget::{column, container, row, scrollable, text};
-use iced::{Background, Color, Element, Fill, Theme};
+use iced::{Color, Element, Fill};
 
 const DIM: Color = Color {
     r: 0.55,

src/ui/tablestyle.rs

@@ -3,7 +3,6 @@
 use crate::app::Message;
 use iced::widget::{
     button, checkbox, column, container, pick_list, row, scrollable, text, text_input, Column,
-    Space,
 };
 use iced::{Background, Border, Color, Element, Fill, Theme};