fix: guard chrome input and stale pane frames

nebula_app/src/input/mod.rs

@@ -1847,6 +1847,17 @@ impl<T: EventListener, A: ActionContext<T>> Processor<T, A> {
                     crate::display::ChromeHit::None => {},
                 }
 
+                // A press inside the chrome band (top bar / tab sidebar) that
+                // hit no control ends here. Falling through used to reach the
+                // terminal's selection arming, which clamps the point into the
+                // nearest grid cell — dragging from the sidebar then painted a
+                // stray selection across the pane (the "drag ghost").
+                let window_size = self.ctx.display().size_info;
+                let scale = self.ctx.window().scale_factor as f32;
+                if crate::display::in_chrome_bar(&window_size, scale, x, y) {
+                    return;
+                }
+
                 // Nebula: grab the scrollback thumb (or jump on a track press).
                 // Only live while scrolled into history, since the bar auto-hides.
                 let view = self.ctx.size_info();

nebula_app/src/window_context.rs

@@ -1924,7 +1924,12 @@ impl WindowContext {
         } else {
             self.display.begin_pane_frame(&self.config);
             let mut dim_rects = Vec::new();
-            for (i, (id, view)) in pane_rects.iter().enumerate() {
+            // The whole-window clear must not be tied to pane_rects[0]: a
+            // layout leaf whose pane is gone (or a doc sentinel) is skipped
+            // below, and skipping the clearing pane would leave every later
+            // frame compositing over stale buffer contents (ghost frames).
+            let mut cleared = false;
+            for (id, view) in pane_rects.iter() {
                 let Some(idx) = self.pane_index(*id) else { continue };
                 let is_focused = *id == focused;
                 if !is_focused {
@@ -1946,8 +1951,9 @@ impl WindowContext {
                     &mut pane.nebula_state,
                     *view,
                     is_focused,
-                    i == 0,
+                    !cleared,
                 );
+                cleared = true;
             }
             self.display.draw_split_overlays(&dim_rects, &divider_rects);
             self.display.finish_pane_frame(scheduler);

nebula_app/src/window_context/split.rs

@@ -411,6 +411,16 @@ impl WindowContext {
     /// focus. Works at any depth, so repeated splits nest into a layout tree
     /// (panes close via the close-pane action).
     pub(super) fn split_focused(&mut self, direction: SplitDirection) {
+        // Doc/settings tabs own no real pane: splitting one would graft the
+        // DOC sentinel leaf into a split tree, whose draw pass then skips it
+        // and leaves that half of the frame stale.
+        if self
+            .tabs
+            .get(self.active_tab)
+            .is_some_and(|tab| tab.doc.is_some() || tab.settings)
+        {
+            return;
+        }
         self.zoom = None;
         let focused = self.focused_pane_id();
         let cwd = self.focused_cwd();