Fix tags crash with preview hidden; Ctrl+B toggles the sidebar

Main.py

@@ -101,6 +101,19 @@ def _BuildWindow(Config, StartPath: Path, **BrowserHooks) -> tuple[ft.Row, Brows
             SidebarView = None
         return Layout
 
+    def OnToggleSidebar() -> None:
+        # Ctrl+B. Hides the existing sidebar instead of rebuilding it, so its
+        # Devices panel keeps its udisks2 connection instead of opening a new one.
+        Config.ShowSidebar = not Config.ShowSidebar
+        Config.Save()
+        if SidebarView is None:
+            OnSidebarSettingsChanged()  # it didn't exist yet (started hidden)
+            return
+        SidebarView.visible = Config.ShowSidebar
+        SidebarView.update()
+        if Config.ShowSidebar:
+            SidebarView.UpdateSelection(BrowserView.CurrentPath)
+
     def OnSidebarSettingsChanged() -> None:
         # Sidebar's presence/side/width and its sections aren't owned by
         # Browser, so rebuilding it lives here rather than needing a restart.
@@ -115,6 +128,7 @@ def _BuildWindow(Config, StartPath: Path, **BrowserHooks) -> tuple[ft.Row, Brows
         OnPathChanged=OnPathChanged,
         OnBookmarksChanged=OnBookmarksChanged,
         OnSidebarSettingsChanged=OnSidebarSettingsChanged,
+        OnToggleSidebar=OnToggleSidebar,
         **BrowserHooks,
     )
     OuterRow.controls = BuildOuterLayout()