Slide animations cause changes in the size requests due to the
behavior of GtkRevealer. We can avoid those by using cross-fades, which
don't have that problem.
Besides, cross-fades look better anyway.
<child type="overlay">
<object class="GtkRevealer" id="controls_revealer">
<property name="valign">end</property>
- <property name="transition-type">slide-up</property>
+ <property name="transition-type">crossfade</property>
<child>
<object class="GtkMediaControls" id="controls">
<style>