Fix broken of running animation - Running animation is stop automatically after a certain time. - It is 300ms according MBScene._updateUI(). - It is caused by notification of changing DOM tree. The notification handlers would call MBScene.updateUI() to update framelines and buttons. - MBScene.updateUI() would call MBScene.show() after 300ms, MBScene.show() calls MBScene.parseScene() in turn. - MBScene.parseScene() would remove duplicate group that is using by code of running animation, MBScene.doRunNext(). It make running animation stop. - fixed by setting MBScene.lockui when a running animation is started or stoped.

<inkscape-extension>
    <name>Edit Button</name>
    <id>MadButterfly.EditButton</id>
	<dependency type="executable" location="extensions">MB_EditButton.py</dependency>
	<dependency type="executable" location="extensions">inkex.py</dependency>
    <effect>
		<object-type>any</object-type>
		<effects-menu>
			<submenu _name="MadButterfly">
				<submenu _name="Button"/>
			</submenu>
		</effects-menu>
    </effect>
    <script>
        <command reldir="extensions" interpreter="python">MB_EditButton.py</command>
    </script>
</inkscape-extension>