Re: pseudo transparency

[Mathias Hasselmann <mathias hasselmann gmx de>]

On Fri, 11 Jan 2002, Olivier Chapuis wrote:

> Hi,
> 
> There is two methods that an application can use to achieve
> "pseudo transparency".
> One method, the E method, is to have a pixmap in memory and
> to indicate the id of this pixmap with a root atom. The second
> method is to use parental relativity.
> Each method has some advantages I do not think that the wm-spec
> should choose one of them. I think that it will be good that
> the wm-spec support both.
> 
> One problem with parental relativity is that a priori the
> application has to set the background of the frame window(s)
> set by the window manager. It seems to me that this leads to
> a bad hack. So I suggest to add a new window state:
> 
>   _NET_WM_STATE_PARENTRELATIVE_BACKGROUND indicates that the window
>   use the ParentRelative pixmap for its background. The window manager
>   should set the frame window(s) background accordingly.

	If you really wan't to have this ugly hack in the WM spec you
should not force window managers to support it by introducing such a flag.
Why: Quite simple for some window managers it just is far too expensive to
implement this feature since implementing it would require to throw away
all assumtions they make about frame windows.

	So my suggestion would be that "parental-relative-background-
aware" window managers just add an atom to the _NET_SUPPORTED root
property: _NET_PARENT_RELATIVE_BACKGROUND or if this feature is not
accepted to become part of the extended window manager spec an atom like
_RXVT_TRANSPARENCY_HACK could be used. Friendly applications using
parental-relative feature just would look for this property and reject/at
least comment the user's wish to enable semi-transparency:

	"Warning: parental relative backgrounds are not supported by the
current window manager."


Ciao,
Mathias
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