VNC Viewer allows a set of options to be saved per-user, which will be used as the defaults for all connections that user makes to VNC Servers. The Default Options can be overridden from the Connection Details dialog, before making a connection, or during a connection, or by specifying the options to override on the VNC Viewer command-line.

VNC Viewer allows any option to be specified on the command-line when it is launched. Options specified on the command-line override those specified in the Default Options dialog. Options configured on the command-line can be changed once a connection has been made, using the Connection Options dialog, though.

AutoSelect=true/false
Auto select

The Auto select check-box controls whether or not VNC Viewer should attempt to automatically gauge the speed of the network connection to the VNC Server and adjust its behaviour accordingly. If selected, the viewer will take control of the graphical compression scheme used, and will only request full colour updates if the network appears fast enough to support them. If not selected, then the user must select suitable encoding and format options manually.

PreferredEncoding=Raw/Hextile/ZRLE
ZRLE
Hextile
Raw

The ZRLE, Hextile and Raw radio buttons allow the preferred graphical encoding used by VNC Viewer to be controlled by the user. The available encodings are arranged in order of increasing bandwidth requirements and decreasing processing requirements, so that ZRLE is most effective on slow networks such as dial-ups, while Raw is often most effective on fast LANs. The preferred encoding is determined automatically by VNC Viewer if the Auto select checkbox is ticked.

Colour level

The Colour level box controls whether VNC Viewer should request as many colours as it and the server can handle, or one of a predefined set of lower-colour, less bandwidth-intensive levels.

FullColour=true/false
Full (all available colours)

If Full Colour mode is selected then VNC Viewer will attempt to render colours as accurately as possible. Otherwise, a reduced number of colours will be used, to limit the required network bandwidth. The reduced colour mode to use is determined by the LowColourLevel setting.

LowColourLevel=2
Medium (256 colours)

LowColourLevel=1
Low (64 colours)

LowColourLevel=0
Very Low (8 colours)

If Full Colour mode is not active then VNC Viewer will instead request one of a set of preset lower colour modes. These modes range from Medium colour, which requests 8bpp palettized pixel data from the server, to Very Low colour, which requests pixel data in 3bpp true-colour format, causing the entire desktop to be rendered in lurid primary colours.

SendPointerEvents=true/false
Send pointer events to server

By default, any pointer actions within the VNC Viewer window will be sent to the VNC server. If this checkbox is unticked then pointer events will no longer be sent, allowing VNC Viewer to operate in a view-only mode.

SendKeyEvents=true/false
Send keyboard events to server

By default, any key presses within the VNC Viewer window will be sent to the VNC server. If this checkbox is unticked then key events will no longer be sent, allowing VNC Viewer to operate in a view-only mode.

SendCutText=true/false
Send clipboard changes to server

By default, any text copied to the clipboard will be sent to the VNC server, so that the remote and local clipboards are synchronised. If this checkbox is unticked then clipboard data will no longer be sent, ensuring that clipboard actions made at the server are not affected by the viewer, and that sensitive data in the local clipboard cannot be leaked to the server.

AcceptCutText=true/false
Accept clipboard changes from server

By default, any text copied to the remote clipboard will be sent by the VNC Server to the VNC Viewer. If this checkbox is unticked then clipboard data sent by the server will be ignored, ensuring that clipboard actions made at the server cannot affect the local clipboard.

Emulate3=true/false
Enable 3-button mouse emulation

When 3-button mouse emulation is enabled, pressing the left and right mouse buttons simultaneously will instead be treated as a middle-button press event. This is used when accessing a system requiring use of all three buttons from a VNC Viewer machine that only has two physical buttons available.

PointerEventInterval=<milliseconds>
Rate-limit mouse move events

Over very slow networks such as dialup connections, mouse event data and mouse event acknowledgements can be a significant bandwidth drain. VNC Viewer can be configured to enforce a minimum interval between consecutive mouse movement events, to reduce traffic to and from the server. If PointerEventInterval is zero then mouse movement events are always sent to the server as soon as they occur. When ticked, this option sets PointerEventInterval to 200ms.

MenuKey=<key-name>
Menu key

Shared=true/false
Share connection (do not disconnect other viewers)

When connecting to a VNC Server, VNC Viewer can request that all other connected viewers are disconnected before the connection continues. If Share connection is ticked then VNC Viewer will not request that other viewers be disconnected. Note that the server may choose to ignore or refuse VNC Viewer's request. Note that this option is only available when configuring the Default Options or when configuring a new connection, not when the connection is already active.

FullScreen=true/false
Full-screen mode

If the Full-screen mode checkbox is ticked then VNC Viewer will attempt to take over the entire local display in order to show the remote desktop. The full-screen setting can be set as a default, used for new connections, and changed once a connection is active. The F8 Menu also provides a shortcut to toggle full-screen mode.

UseLocalCursor=true/false
Render cursor locally

VNC Viewer 4 supports rendering of the VNC Server's cursor locally, by the viewer. This means that the cursor responds more quickly to mouse movemements and makes VNC connections over slow networks appear faster. Over faster networks, or for personal preference, this local rendering may be disabled by unticking the Render cursor locally checkbox.

UseDesktopResize=true/false
Allow dynamic desktop resizing

VNC Viewer 4 supports dynamic resizing of the VNC Server desktop. If dynamic resizing is not supported by both viewer and server then changes to the dimensions of the remote desktop may cause the VNC connection to be closed. Dynamic desktop resizing may be disabled if it causes problems on your system.

Protocol3.3=true/false
Only use protocol version 3.3

VNC Viewer 4 supports both the original VNC version 3.3 protocol, and the new VNC protocol versions 3.7 and 3.8. Some third-party VNC software use non-standard version numbers which may cause incompatibility issues. VNC Viewer 4 can therefore be configure to only ever use the original VNC protocol version 3.3, ensuring compatibility even with non-standard VNC Servers. Note that this option may be set as a Default Option, or when making a new connection, but cannot be changed once a connection is active.

AcceptBell=true/false
Beep when requested to by the server

By default, VNC Viewer 4 will play a default system beep when sent a bell event by VNC Server. The beep can be disabled by setting AcceptBell to false.