The selection should be visible in the "partial" charts if it crosses the current visible time range. It should be always visible in the "full-range" charts. Left-clicking and dragging into the chart area should also set the selection.
Broken down in different tasks:
[x] Display current selection range in full-range widget.
[x] Display current selection range in visible-range widget.
[x] Allow time range selection (and showing "ongoing" selection) in full-range widget.
[x] Allow time range selection (and showing "ongoing" selection) in visible-range widget.
The selection should be visible in the "partial" charts if it crosses the current visible time range. It should be always visible in the "full-range" charts. Left-clicking and dragging into the chart area should also set the selection.
Broken down in different tasks: