Ok so I've gotten around the problem by using systray-lsbox.dll and an LsBox as an anchor for the systray. The image of the systray is the LsBox image, and the systray's background is just a solid color that matches the color of the area in the box image where the systray sits. (Hope that made sense to everyone)

Now here's the complicated bit. To enable auto-sizing, I employed the following systray.rc:



...also the script vars TrayWidth and TrayPos, pre-defined either in a startup script or in a vars.rc file, and the following script:



Hope this helps anyone else trying to overcome this little problem :)