Failing to restore filtered time period

[IanMayo]

When an analyst filters a plot to a specific time period, and the file is saved in .dpf format, Debrief should restore that filtered period when the file is re-opened.

While it does appear that Debrief is restoring the filtered time period, it then expands to show the full data. This does seem to be an emergent issue, though it could have emerged in the last 18 months.

Update: - aah, I've learned a little more. The analyst that reported the issue contacted me again the next week, to indicate that the issue was now fixed for her. That seemed strange, since Debrief hadn't been updated. I think I've guessed the cause. If the analyst has "filter to time period" clicked, then when we load a new plot, and set the sliders to where they were before, then Debrief will filter the data. If the analyst doesn't have it clicked, then when the sliders are set, the plot won't be filtered. That may be what's happening. If it is, then we should probably store the value of filter to time period" in the element in the.dpf` file.