X Error: BadCursor

[iam_peter]

hi,

iam getting an X Error when my application starts:

@X Error: BadCursor (invalid Cursor parameter) 6
Major opcode: 2 (X_ChangeWindowAttributes)
Resource id: 0x2
@

My application consists of a QMainWindow and several QDockWidgets.
Everytime the cursor is over a border of a QDockWidget and it changes from Qt::SizeVerCursor/Qt::SizeHorCursor
to the default Qt::ArrowCursor it gives my the following warning:

@QCursor::update: Invalid cursor shape 25@

This is my system configuration:

Ubuntu 11.04
Kernel Linux 2.6.38-13-generic
GNOME 2.32.1

i tested the application with qt 4.7.4 and 4.8.1, but the cursor warnings are the same.
Any ideas how to solve it?

Regards,
peter