<b>Time window</b>

The window is how much time the plot shows. Every row shares one window: the figure has a
single x link group, so the rows cannot drift apart. The trigger's event span follows it, and
the pre-trigger share is a share of <i>this</i> window.

<b>How to reach it</b>

The header bar's window button opens a popover: type a number, pick a unit under it, or step a
decade with the arrows. The button's own label is a reading of the current window in a natural
unit, width-locked so a change of window cannot widen the header bar.

<b>Worth knowing</b>

• A window too long to store at the wire rate is <i>decimated, not refused</i>. The shared clock
  takes a power-of-two stride, and each group of samples is <b>averaged</b> rather than strided,
  so a tone above the stored Nyquist is attenuated instead of aliasing to a false low frequency.
• The stamp stored for a group is the group's <i>mean</i>, which is where the averaging puts the
  value. Stamping at the end of a group would shift every trace half a stored sample late.
• Moving the window across a decimation boundary rebuilds the buffer and drops the history.
  Walking it inside one decade is free.
• The trigger sees the <i>stored</i> (filtered) signal, not the wire signal, because an edge
  found on a sample that is not in the buffer could not be cut out of it.

<b>Example</b>

1 MS/s with 200 MB of buffer. A 2 s window stores every sample (<tt>time x1</tt>). Widen it to
600 s and the stride becomes <tt>x16</tt>: 625 S/s stored, anti-aliased at 312.5 Hz. A 2 kHz
sine seen through that window reads <tt>y=[-0.059, 0.079]</tt> — attenuated to about 6%, not
folded down to a full-amplitude 125 Hz one.
