> It has a bug. The filter will fail on the initial page of the logbook. 
> 
> example,
> 
> on http://10.10.10.10:10/mylogbook/  
> when select category filter the system will return
>       http://10.10.10.10:10/myylogbook/&category=hardware which is bad
> 
> on http://10.10.10.10:10/mylogbook/page or page1/page2 etc..other then the initial page,
> when select category filter the system return the correct result.
>       http://10.10.10.10:10/mylogbook/page?category=hardware.
> 
> I have not tested 2.5.3.

You should, it has been fixed in 2.5.3 :-)))