Refactor module layout

data/ui/editor/tracks/parts_popover.blp

@@ -0,0 +1,35 @@
+using Gtk 4.0;
+using Adw 1;
+
+template $MusicusTracksEditorPartsPopover: Gtk.Popover {
+  styles [
+    "selector"
+  ]
+
+  Adw.ToolbarView {
+    [top]
+    Gtk.SearchEntry search_entry {
+      placeholder-text: _("Search parts…");
+      margin-start: 8;
+      margin-end: 8;
+      margin-top: 8;
+      margin-bottom: 6;
+      search-changed => $search_changed() swapped;
+      activate => $activate() swapped;
+      stop-search => $stop_search() swapped;
+    }
+
+    Gtk.ScrolledWindow scrolled_window {
+      height-request: 200;
+
+      Gtk.ListBox list_box {
+        styles [
+          "selector-list"
+        ]
+
+        selection-mode: none;
+        activate-on-single-click: true;
+      }
+    }
+  }
+}

data/ui/editor/tracks/track_row.blp

@@ -0,0 +1,38 @@
+using Gtk 4.0;
+using Adw 1;
+
+template $MusicusTracksEditorTrackRow: Adw.ActionRow {
+  title: _("Select parts");
+  activatable: true;
+  activated => $select_parts() swapped;
+
+  [prefix]
+  Gtk.Box select_parts_box {
+    Gtk.Image {
+      icon-name: "document-edit-symbolic";
+    }
+  }
+
+  Gtk.Button reset_button {
+    icon-name: "edit-clear-symbolic";
+    tooltip-text: _("Clear selected work parts");
+    visible: false;
+    valign: center;
+    clicked => $reset() swapped;
+
+    styles [
+      "flat"
+    ]
+  }
+
+  Gtk.Button {
+    icon-name: "user-trash-symbolic";
+    tooltip-text: _("Remove this track");
+    valign: center;
+    clicked => $remove() swapped;
+
+    styles [
+      "flat"
+    ]
+  }
+}