Missing minimise and maximise buttons

[brian]

I've been using XFCE for some while with no problem, and when my wife
decided she'd had enough with the Plasma desktop in the latest KDE, I
persuaded her to let me switch her to XFCE. We're both running plain
Debian (she's tracking wheezy, I'm tracking sid).

The problem I have with her setup, which is NOT reproduced on mine, is
that the minimise and maximise buttons are missing from all her
applications - and it's not the case that the application is off the
edge of the screen, even with applications which occupy significantly
less than the full screen on startup, they're not there. Her list of
applications is a little restricted - she runs mainly Icedove (a.k.a.
Thunderbird), Chromium and Libre Office writer and spreadsheet.

I'm at a total loss to understand why this happens. Once I switch her
back to KDE, they reappear, the change is reversible. Does anyone have
any ideas?


Thanks,

Brian.