[ROOT] Re: GUI classes and X11 errors

From: Greg Novak (novak@post.harvard.edu)
Date: Thu Sep 07 2000 - 16:09:54 MEST


I apologize about the previous posting; these are the files I meant to
send.

Thanks,
Greg

On Thu, 7 Sep 2000, Greg Novak wrote:

> I'm writing an application that uses the Root GUI classes, TG*, and I'm
> using Root 2.23/12 on a machine running Red Hat 6.1. 
> 
> I have one window where a button performs a long computation and then
> deletes the window itself.  I have found that if I place another window
> over certain widgets while the computation is running (so that they need
> to be redrawn), then I get errors like the following when the window tries
> to delete itself:
> 
> Error in <RootX11ErrorHandler>: BadDrawable (invalid Pixmap or Window 
> parameter) (XID: 54526074)
> 
> It seels that what's causing this problem are two TGLabel objects.  I
> never need them after I put them in the window, so I didn't bother to keep
> a pointer to them.  Do I need, instead, to keep a pointer to every GUI
> object I create and then delete them in a particular order?
> 
> Also, what is the memory management paradigm for these classes?  Looking
> at the guitest.cxx example, it seems that I only have to give names to
> object I need to access later (TGTextEntry objects for instance, where I
> need to call GetText() to get the string a user entered).  I assume, then,
> that when I create a widget and add it to a window, the window then frees
> the widget's memory when the window is destroyed.  Is this correct?
> 
> I've attached the offending code, stripped of unimportant details.  The
> main part I've left intact is the object construction/destruction.
> 
> Thanks!
> Greg
> 






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