era scrolling. <code>0</code> = no movement (e.g. a background layer),
<code>1</code> = same movement speed as the foreground. Default value is <code>(1,1)</code>,
except for UI elements like <code><a href="../flixel/ui/FlxButton.html#FlxButton">FlxButton</a></code> where it's <code>(0,0)</code>.</p></div></div><div class="field "><a name="solid"></a><h3 class="anchor"><code><a href="#solid"><span class="identifier">solid</span></a>:<a class="type" title="Bool - The standard Boolean type, which can either b