The preview Preview window renders a composition in real-time realtime and includes all components except the Just Out engine output, which will be - once on air playing out-the element playing in the video track once it goes On Air.
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Send Trigger (lower left): Continues the composition if a stop frame has been reached.
State (lower middle): Shows the current status of the preview Preview.
Reload (lower right): Rewinds Rewind the preview Preview.