[gst-devel] 'start of stream' signal, like 'eos'

[Kang Jeong-Hee]

for example, put a toggle button which is play button.
I wanna display status of playing by the toggled.
i.e. connect 'eos' signal to element to make button untoggled.
but I have no clue how can I make button toggled naturally.
I'm sure that I know there are many workaround like manually give 
toggled.
but I think eos alone is out of expect; he needs her. ;)