Document clearing of Traffic and Device panes

docs/source/user_interface.rst

@@ -10,10 +10,10 @@ Across the top of the Packetry window is the Action Bar used to control Packetry
 .. image:: ../images/action-bar.png
   :alt: Action Bar
 
-- **Open Button**: Loads a ``.pcap`` file with the ``LINKTYPE_USB_2_0`` link-layer header type.
+- **Open Button**: Clears Traffic Pane and Device Pane and loads a ``.pcap`` file with the ``LINKTYPE_USB_2_0`` link-layer header type.
 - **Save Button**: Saves a ``.pcap`` file with the ``LINKTYPE_USB_2_0`` link-layer header type.
 - **Scan Button**: Searches for a capture device such as a Cynthion running analyzer gateware.
-- **Capture Button**: Starts capturing USB data with the connected capture device.
+- **Capture Button**: Clears Traffic Pane and Device Pane and starts capturing USB data with the connected capture device.
 - **Stop Button**: Stops capturing USB data. Stops reading USB data from file.
 - **Device Drop-down**: Selects a capture device. If you don't see a device listed here, try using the Scan button.
 - **Speed Drop-down**: Selects the target device speed for live capture.
@@ -31,6 +31,8 @@ The Traffic Pane displays packets in an interactive hierarchical view, allowing
 
 Each packet is displayed with a precise time stamp relative to the start of capture. Higher level groups have a time stamp matching the first packet that is a part of the group.
 
+The Traffic Pane is cleared at the start of each capture or when a file is loaded.
+
 
 Device Pane
 -----------
@@ -42,6 +44,8 @@ To the right of the Traffic Pane is the Device Pane. The Device Pane summarizes
 
 Much of the information that can be displayed in the Device Pane is discovered only if Packetry observes the initial enumeration of a USB device by the target host. To allow this to take place in a live capture, connect the target device after starting a capture, not before.
 
+The Device Pane is cleared at the start of each capture or when a file is loaded.
+
 
 Detail Pane
 -----------