http://bugs.winehq.org/show_bug.cgi?id=19689
--- Comment #5 from Richardcavell@mail.com richardcavell@mail.com 2009-08-11 19:07:17 --- Okay, my bad. I had "Allow the window manager to control the windows" disabled, in order to workaround the Steam menu flickering problem that is mentioned elsewhere in bugzilla. I was correctly enabling and disabling it, but because Steam stayed resident in the tray throughout my experiments, rather than being reloaded, it was not being affected by the changes.
So the solution is: Enable "Allow the window manager to control the windows", and learn to put up with flickering.