Moodbar-Trackslider uses the full available height

When determining the next state (for rendering the change), the slider widgets vertical SizePolicy is changed from Fixed to MinimumExpanding (same thing works the other way around).

src/moodbar/moodbarproxystyle.cpp

@@ -98,6 +98,12 @@ void MoodbarProxyStyle::SetMoodbarEnabled(bool enabled) {
 void MoodbarProxyStyle::NextState() {
   const bool visible = enabled_ && !data_.isEmpty();
 
+  // While the regular slider should stay at the standard size (Fixed),
+  // moodbars should use all available space (MinimumExpanding).
+  slider_->setSizePolicy(QSizePolicy::Expanding,
+      visible ? QSizePolicy::MinimumExpanding : QSizePolicy::Fixed);
+  slider_->updateGeometry();
+
   if (show_moodbar_action_) {
     show_moodbar_action_->setChecked(enabled_);
   }