Update the packet list documentation.

Update images and describe related packets and the intelligent
scrollbar. Suggest a way to make it easier to get a screenshot of
related packets.

Change-Id: I5bf27b0c53fb62f3e567765400141a374a465e4e
Reviewed-on: https://code.wireshark.org/review/13159
Reviewed-by: Gerald Combs <gerald@wireshark.org>

docbook/CMakeLists.txt

@@ -77,6 +77,15 @@ set(WSUG_FILES
 )
 
 set(WSUG_GRAPHICS
+	wsug_graphics/related-ack.png
+	wsug_graphics/related-current.png
+	wsug_graphics/related-dup-ack.png
+	wsug_graphics/related-first.png
+	wsug_graphics/related-last.png
+	wsug_graphics/related-other.png
+	wsug_graphics/related-request.png
+	wsug_graphics/related-response.png
+	wsug_graphics/related-segment.png
 	wsug_graphics/ws-analyze-menu.png
 	wsug_graphics/ws-bytes-pane-tabs.png
 	wsug_graphics/ws-bytes-pane.png

docbook/wsug_src/WSUG_chapter_use.asciidoc

@@ -781,7 +781,7 @@ The packet list pane displays all the packets in the current capture file.
 
 [[ChUseWiresharkListPane]]
 .The ``Packet List'' pane
-image::wsug_graphics/ws-list-pane.png[]
+image::wsug_graphics/ws-list-pane.png[scaledwidth="100%"]
 
 Each line in the packet list corresponds to one packet in the capture file. If
 you select a line in this pane, more details will be displayed in the ``Packet
@@ -814,9 +814,61 @@ The default columns will show:
 
 * button:[Protocol] The protocol name in a short (perhaps abbreviated) version.
 
+* button:[Length] The length of each packet.
+
 * button:[Info] Additional information about the packet content.
 
-There is a context menu (right mouse click) available, see details in
+The first column shows how each packet is related to the selected packet. For
+example, in the image above the first packet is selected, which is a DNS
+request. Wireshark shows a rightward arrow for the request itself, followed by a
+leftward arrow for the response in packet 2. Why is there a dashed line? There
+are more DNS packets further down that use the same port numbers. Wireshark
+treats them as belonging to the same conversation and draws a line connecting
+them.
+
+// Images were created on OS X 10.11 using a retina display. Lines were
+// 36 physical pixels high.
+
+[horizontal]
+.Related packet symbols
+
+image:wsug_graphics/related-first.png[height="18px"]::
+  First packet in a conversation.
+
+image:wsug_graphics/related-current.png[height="18px"]::
+  Part of the selected conversation
+
+image:wsug_graphics/related-other.png[height="18px"]::
+  _Not_ part of the selected conversation
+
+image:wsug_graphics/related-last.png[height="18px"]::
+  Last packet in a conversation.
+
+image:wsug_graphics/related-request.png[height="18px"]::
+  Request.
+
+image:wsug_graphics/related-response.png[height="18px"]::
+  Response.
+
+image:wsug_graphics/related-ack.png[height="18px"]::
+  The selected packet acknowledges this packet.
+
+image:wsug_graphics/related-dup-ack.png[height="18px"]::
+  The selected packet is a duplicate acknowledgement of this packet.
+
+image:wsug_graphics/related-segment.png[height="18px"]::
+  The selected packet is related to this packet in some other way, e.g. as part
+  of reassembly.
+
+The packet list has an _Intelligent Scrollbar_ which shows a miniature map of
+nearby packets. Each https://en.wikipedia.org/wiki/Raster_graphics[raster line]
+of the scrollbar corresponds to a single packet, so the number of packets shown
+in the map depends on your physical display and the height of the packet list. A
+tall packet list on a high-resolution (``Retina'') display will show you quite a
+few packets. In the image above the scrollbar shows the status of more than 500
+packets along with the 15 shown in the packet list itself.
+
+Right clicking will show a context menu, described in
 <<ChWorkPacketListPanePopUpMenu>>.
 
 [[ChUsePacketDetailsPaneSection]]

ui/qt/related_packet_delegate.cpp

@@ -111,6 +111,10 @@ void RelatedPacketDelegate::paint(QPainter *painter, const QStyleOptionViewItem
     // The current decorations are based on what looked good and were easy
     // to code.
 
+    // It might be useful to have a JACKPOT_MODE define that shows each
+    // decoration in sequence in order to make it easier to create
+    // screenshots for the User's Guide.
+
     // Vertical line. Lower and upper half for the start and end of the
     // conversation respectively, solid for conversation member, dashed
     // for other packets in the start-end range.