Re: [Texmacs-dev] Qt-TeXmacs: segfault with KDE-Oxygen

[Gubinelli Massimiliano]

Hi Norbert,

 the status of the Qt port under Linux is not ideal. The main reason  
is that I'm developing the port under Mac and currently, due to lack  
of time, I'm not able to cross-test under Linux. I should mention that  
the Qt port works under mac and windows (in the sense that it does not  
segfaults like it does on linux). I've done some experimentations with  
different versions of Qt/X11 under Linux and for example the port  
works fine with the 4.4/debug version of the libraries. I don't thinks  
there is a real bug. I tend to think that the use of the Qt framework  
forced by TeXmacs structure is a bit unconventional and produce  
fragile code.

As far as the run-loop is concerned we tried different alternatives  
(both in Qt port and in the Cocoa port) the main constraint we have to  
face is that there should be some order in the call to  
the_interpose_handler (see qt_gui.cpp for example) which perform the  
update of internal TeXmacs structures after some inputs and the  
refresh of the exposed widgets. In the X11 port everything is  
carefully crafted by exaclty prescribing the order of operations :  
input handling, update, refresh. In modern GUIs like Qt or Cocoa  
usually the run-loop is controlled by the library and we haven't fund  
canonical ways to correclty sequence the calls to TeXmac internal  
functions (both for updating and refreshing).

I should mention also the fact that we have a cario renderer available  
and that if the problems with the Qt port cannot be reasonably  
resolved (for example now I found a bug apparently due to Qt) we  
should evaluate the option to shift to other cross-platform libraries  
like Gtk+ or wxWidgets, or the like.

Any suggestion to improve the status of the Qt port under linux is  
welcome.

Best,
Massimiliano

On 19 avr. 09, at 19:21, Norbert Nemec wrote:

> Hi there,
>
> I just tracked down the segfaults of Qt-TeXmacs to the use of the  
> Oxygen style in KDE. When I have that style active, TeXmacs crashes  
> as soon as I click on a menu that contains sub-menus. Menus without  
> sub-menus work fine.
>
> The simple solution: use a different style.
>
> I fear the bug really sits in TeXmacs not in the style. I have never  
> experienced problems with the style in any other setting. My guess  
> would be that the menus are set up in some strange way that usually  
> works but does not really follow the standards and causes problems  
> in this special case.
>
> Greetings,
> Norbert
>
>
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