Always show a scrollbar in the smart playlist preview (avoids flickering when the viewport resizes), and stop the new search term widget responding to mouse events when it's disabled

src/smartplaylists/searchpreview.ui

@@ -65,6 +65,9 @@
    </item>
    <item>
     <widget class="PlaylistView" name="tree">
+     <property name="verticalScrollBarPolicy">
+      <enum>Qt::ScrollBarAlwaysOn</enum>
+     </property>
      <property name="rootIsDecorated">
       <bool>false</bool>
      </property>

src/smartplaylists/searchtermwidget.cpp

@@ -159,7 +159,7 @@ void SearchTermWidget::SetActive(bool active) {
 }
 
 void SearchTermWidget::enterEvent(QEvent*) {
-  if (!overlay_)
+  if (!overlay_ || !isEnabled())
     return;
 
   animation_->stop();