Returns the frame counter for the oldest frame available in history.
`GdkFrameClock` internally keeps a history of `GdkFrameTimings` objects for recent frames that can be retrieved with [ [email protected]_timings]. The set of stored frames is the set from the counter values given by [ [email protected]_history_start] and [[email protected]_frame_counter], inclusive.
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a `GdkFrameClock` |
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the frame counter value for the oldest frame that is available in the internal frame history of the `GdkFrameClock` |