A progress bar indicating the current playback location of a
video, defined within <video_defaults>.
Child of: <video_defaults>
Parent of: <x>,
<y>, <height>, <width>, <edge>, <fill_color>,
<file>
See also: <popup>,
Example:
<bar>
<x>10</x>
<y>220</y>
<height>26</height>
<width>280</width>
<edge>4</edge>
<fill_color>0x6BA668</fill_color>
<file>http://www.my_site.com/my_progress_bar.png</file>
</bar>