Bug in Qt 4.6.2?

[lukass]

Hello.

I have small application code, which demonstrates difference between running this program on Windows and Linux.

On Linux - Qt 4.6.2(correct behavior):
1) run program,
2) click right mouse button on "Data" row in table - context menu will show up,
3) click left mouse button(not in context menu) on "Data" row in table - context menu will hide

On Windows XP - Qt 4.6.2(wrong behavior):
1) run program,
2) click right mouse button on "Data" row in table - context menu will show up,
3) click left mouse button(not in context menu) on "Data" row in table - context menu will hide
- QMessageBox will show up.

Working app(source code) is in attachment.

Is this bug in Qt 4.6.2?
How can I fix this in my app?