nav: only save columns once

Before we would save columns for each rendered nav. Now we only do it
once.

src/app.rs

@@ -744,8 +744,10 @@ fn render_damus_mobile(ctx: &egui::Context, app: &mut Damus) {
     //let routes = app.timelines[0].routes.clone();
 
     main_panel(&ctx.style(), ui::is_narrow(ctx)).show(ctx, |ui| {
-        if !app.columns.columns().is_empty() {
+        if !app.columns.columns().is_empty()
-            nav::render_nav(0, app, ui).process_render_nav_response(app);
+            && nav::render_nav(0, app, ui).process_render_nav_response(app)
+        {
+            storage::save_columns(&app.path, app.columns().as_serializable_columns());
         }
     });
 }
@@ -822,6 +824,7 @@ fn timelines_view(ui: &mut egui::Ui, sizes: Size, app: &mut Damus) {
                 );
             });
 
+            let mut save_cols = false;
             let mut responses = Vec::with_capacity(app.columns.num_columns());
             for col_index in 0..app.columns.num_columns() {
                 strip.cell(|ui| {
@@ -840,7 +843,12 @@ fn timelines_view(ui: &mut egui::Ui, sizes: Size, app: &mut Damus) {
             }
 
             for response in responses {
-                response.process_render_nav_response(app);
+                let save = response.process_render_nav_response(app);
+                save_cols = save_cols || save;
+            }
+
+            if save_cols {
+                storage::save_columns(&app.path, app.columns().as_serializable_columns());
             }
         });
 }

src/nav.rs

@@ -7,7 +7,6 @@ use crate::{
     profile::Profile,
     relay_pool_manager::RelayPoolManager,
     route::Route,
-    storage::{self},
     thread::Thread,
     timeline::{
         route::{render_timeline_route, TimelineRoute},
@@ -60,7 +59,8 @@ impl RenderNavResponse {
         RenderNavResponse { column, response }
     }
 
-    pub fn process_render_nav_response(&self, app: &mut Damus) {
+    #[must_use = "Make sure to save columns if result is true"]
+    pub fn process_render_nav_response(&self, app: &mut Damus) -> bool {
         let mut col_changed: bool = false;
         let col = self.column;
 
@@ -146,9 +146,7 @@ impl RenderNavResponse {
             }
         }
 
-        if col_changed {
+        col_changed
-            storage::save_columns(&app.path, app.columns().as_serializable_columns());
-        }
     }
 }