Alternate shortcut Escape (Esc) is set but becomes disabled by QMenu activity

Product
Qt
Function
MainWindow
Version
4.5.1
Platform
Linux
Platform details
Dell Inspiron 6400 laptop. KDE 4.3 and 4.4 development trunk.
Compilers
GCC
Compiler details
Subject
Alternate shortcut Escape (Esc) is set but becomes disabled by QMenu activity
Steps to reproduce / test case
This problem appears to be in QMenuBar, but it arose originally in KDE/trunk/kdegames/kgoldrunner/src That program uses KDE Games standard shortcut P for the Pause action and also the Escape key as an alternate shortcut. After certain menubar operations, the Escape shortcut can become disabled. This was reported as a KDE bug at https://bugs.kde.org/show_bug.cgi?id=197686 ... with a description of how to reproduce the bug.

The KDE team has narrowed the problem down to how QMenuBar releases keyboard focus and has provided a short Qt-only program to reproduce the problem and suggest a fix, see http://bugs.kde.org/attachment.cgi?id=37414
More information
See the full discussion at https://bugs.kde.org/show_bug.cgi?id=197686

I have a workaround, suggested by one of the KDE team, in which the central widget, a pure-graphics widget, sets a keyboard focus policy, although it ought not to be necessary in such a widget.