[PyOpenGL] multiple screens and Tkinter/Togl

[Rene Liebscher]

Michel Sanner wrote:
> 
> Hello,
> 
> I have 2 screens on my unix box and I can use the screenName argument to get a
> Tkinter.Tk instance to appear on either screen. But when I try to create an togl
> Widget I get an Xserver error that kills my python interpreter. Here is the code
> creating the problem
> 
> import Tkinter
> r1 = Tkinter.Tk(screenName=":0.0")
> r1.tk.call('package', 'require', 'Togl')
> r2 = Tkinter.Tk(screenName=":0.1")
> r2.tk.call('package', 'require', 'Togl')
> f1 = Tkinter.Frame(r1)
> f2 = Tkinter.Frame(r2)
> f1.pack()
> f2.pack()
> 
> class OGL(Tkinter.Widget):
>     def __init__(self, master, ident):
>         cnf = ()
>         kw = {'double':1} #, 'depth':1, 'accum':1, 'ident':ident}
>         Tkinter.Widget.__init__(self, master, 'togl', cnf, kw )
> 
> o1 = OGL(f1, '1')
> o2 = OGL(f2, '2')
> 
> X Error of failed request:  BadMatch (invalid parameter attributes)
>   Major opcode of failed request:  1 (X_CreateWindow)
>   Serial number of failed request:  149
>   Current serial number in output stream:  151
> 
> My 2 screens have different resolution and depth but it does not seem to be a
> problem for regulat Tk widgets.
> 
> I am also wondering if the fact the screenName is an argument to Tk means that a
> Tkinter application cannot have windows on 2 screens at the same time (unless
> they do not share the same interpreter).
> 
> Any Ideas or comments would be very welcome
> 
> -Michel
> 
This might be a problem in Togl.

I don't know enough about X to find the problem, but 
I found the following.


In togl.c there are some uses of the DefaultScreen macro.
For this macro I found these description:
-----------------------------------------------
DefaultScreen

DefaultScreen(display)

int XDefaultScreen(display)
      Display *display;


display  Specifies the connection to the X server.  

Both return the default screen number referenced by the XOpenDisplay()
function. 
This macro or function should be used to retrieve the screen number in
applications 
that will use only a single screen.
-----------------------------------------------
You see that "in applications that will use only a single screen."

It might help to change this.
(See also
http://sourceforge.net/tracker/index.php?func=detail&aid=222132&group_id=519&atid=100519
there is also a description of a problem with DefaultScreen,
They recommend to use Tk_ScreenNumber(togl->TkWin) )


The XCreateWindow function has no parameter screen, 
but the call of glXChooseVisual has. Using a wrong screen parameter
here might lead to a wrong visual which makes XCreateWindow
to complain about it.  

I don't know if any of these hints help, but if it works we 
should put it in the CVS.


Kind regards
Rene