The tray manager should set the following hints on the selection owner window.
_NET_SYSTEM_TRAY_ORIENTATION orientation CARDINAL/32 #define _NET_SYSTEM_TRAY_ORIENTATION_HORZ 0 #define _NET_SYSTEM_TRAY_ORIENTATION_VERT 1
The property should be set by the tray manager to indicate the current orientation of the tray. Tray icons may use this hint in order to maintain the icon's aspect ratio and also as an indication of how the icon contents should be laid out.
_NET_SYSTEM_TRAY_VISUAL visual_id VISUALID/32
The property should be set by the tray manager to indicate the preferred visual for icon windows. To avoid ambiguity about the colormap to use this visual must either be the default visual for the screen or it must be a TrueColor visual. If this property is set to a visual with an alpha channel, the tray manager must use the Composite extension to composite the icon against the background using PictOpOver.