Brendan,
I’m afraid this problem is specific to Linux 64 but works on Linux 32. Technically we need shift to a different version of XULRunner but we cannot do that only for Linux 64, we need to do it across the code base leading to significant risk as it isn’t a simple replacement.
We do have this targeted for MyEclipse 11 – our experiments have shown that the newer version of XULRunner will fix the problem. Until then, the only workaround I can suggest is to use a 32bit install of MyEclipse for the Ajax browser.
Sorry for the inconvenience caused.