use bottom sheet for playbar

src/ui/play_queue.blp

@@ -16,6 +16,7 @@ template $UiPlayQueue: Adw.NavigationPage {
 
     ScrolledWindow {
       ListView view {
+        show-separators: true;
         single-click-activate: true;
 
         activate => $on_row_activated ();

src/ui/window.blp

@@ -6,10 +6,11 @@ template $UiWindow: Adw.ApplicationWindow {
   default-width: 800;
   default-height: 600;
 
-  content: Box {
-    orientation: vertical;
-
+  content: Adw.BottomSheet bottom_sheet {
+    [content]
     Adw.OverlaySplitView {
+      margin-bottom: bind bottom_sheet.bottom-bar-height;
+
       vexpand: true;
 
       [sidebar]
@@ -88,7 +89,10 @@ template $UiWindow: Adw.ApplicationWindow {
       }
     }
 
-    [bottom]
+    [sheet]
+    Box {}
+
+    [bottom-bar]
     CenterBox {
       styles [
         "toolbar",