Plasma and KWin Integration

[Richard Moore]

Hi All,

Here's the write up of the kwin and plasma integration discussion at Tokamak.

Cheers

Rich.

Plasma and KWin Integration
===========================

This is the results of the discussion on the areas we (the plasma team) feel
we need help from the kwin team to produce better integration. It's a mixture
of issues from fairly trivial ones, through complex ones, to those that come
down to issues with specifications like NETWM. The aim is to provide users
with the best possible experience running a pure-KDE desktop.

1. Ability to obtain pixmaps of windows.

There are a number of effects that would be possible within plasma and other
applications if it was possible to obtain a full pixmap of a window (even if
it is obscured). This information is available to kwin and used for
compositing, the idea would be to publish it for use by other applications.

Our idea was that maybe this could be handled in a suitably performant way by
using QPixmaps that share an XPixmap handle between both kwin and the client
application (plasma in our case).


2. Better thumbnail scaling.

The scaling algorithm used by kwin to create the window thumbnails seems to
produce pretty poor results, comparing the results with Qt's smooth scale for
example. Looking at the code, they appear to be using a codepath that
generically supports all the transformations used in effects. Could we get
better results by having a codepath that is specifically designed for scaling?

3. Ability to have windows on a specific set of virtual desktops.

Being able to say a window is on desktop 1 and 3 for example. This one isn't a
big deal, just a 'nice to have'.


4. Per-desktop struts.

At the moment struts apply to all desktops, which doesn't make sense if (for
example) you have different panel configurations on different desktops. It
could also be an issue if a particular desktop was a full-screen media center,
though in this latter case it can be worked around.


5. Shadows of shaped windows.

At the moment the shadows of shaped windows don't really work, could we have
something like a separate shadow mask?


6. Marco created a patch that added a shadow to the plasma panel, and whilst
kwin handled the strut correctly in some cases, it did not in others. For
example, the magnetic window borders stuck to the shadow rather than to the
edge of the panel.


7. Theming of kwin dialogs to match the rest of the desktop furniture.

Things like the window menu are part of the desktop rather than part of
applications and it would be great if they were coloured like the other pieces
of furniture rather than like the applications they manage. The same thing
applies to a number of other things drawn by kwin such as in the box switch
effect.


8. Document modal windows.

Having a way to handle document-modal windows along the lines of the Sheets in
MacOS. These would be positioned over their parent window and move with the
parent.


9. Hide the panel when zooming out to show the containments.

As discussed already by Sebas, and patch provided.


10. Alt-Tab to desktop and panel

The desktop and panel need to be able to get the keyboard focus to allow users
without keyboards to activate and use them.