My KWIN fork where I work on features like per-output virtual desktops
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Martin Gräßlin bf99d9ffdd Introduce support for keyboard layout switching policies
Summary:
This change introduces the initial support for keyboard layout switching
policies like in the X11 session. This first change only adds support for
Global and Virtual Desktop policy. This means the current layout is
stored in context to the current virtual desktop. Whenever one changes
the virtual desktop the previous layout is restored. If the user has not
yet navigated to this virtual desktop a switch to default layout is
performed.

This is the first code interacting with the new Virtual Desktop API which
is not based on integer ids. To fully support this the API is slightly
extended.

Test Plan: Added test case

Reviewers: #kwin, #plasma

Subscribers: plasma-devel, kwin

Tags: #kwin

Differential Revision: https://phabricator.kde.org/D5301
2017-04-22 08:15:25 +02:00
autotests Introduce support for keyboard layout switching policies 2017-04-22 08:15:25 +02:00
cmake/modules [plugins/qpa] support use of modularized qtplatformsupport from Qt 5.8 2016-10-28 21:12:48 +09:00
data [plugins/qpa] Add debug output for the KWin internal QPA plugin 2016-07-18 16:34:03 +02:00
decorations Restore global menu support 2017-01-11 10:21:03 +01:00
doc Update windowspecific (Window Rules) docbook 2016-10-04 18:46:51 +02:00
effects [effects/slideback] Consider windows which do have painting disabled as not usable 2017-04-20 17:03:12 +02:00
helpers Merge branch 'Plasma/5.8' 2016-11-07 11:41:30 +01:00
kcmkwin SVN_SILENT made messages (.desktop file) - always resolve ours 2017-04-20 04:17:52 +02:00
libinput Require Qt 5.7 and remove pre-5.7 code 2017-02-07 20:43:19 +01:00
libkwineffects [effects] Use arg="true" in the kcfg files 2017-04-15 10:03:34 +02:00
packageplugins SVN_SILENT made messages (.desktop file) - always resolve ours 2017-04-16 04:05:25 +02:00
plugins [platforms/x11] Do not grab touch events 2017-04-20 17:03:38 +02:00
qml Require Qt 5.7 and remove pre-5.7 code 2017-02-07 20:43:19 +01:00
scripting Fix two more const / non-const iterator mismatches. 2017-04-07 20:38:19 +02:00
scripts SVN_SILENT made messages (.desktop file) - always resolve ours 2017-03-25 06:02:34 +01:00
shaders [libkwinglutils] Cleanup Shader API: removal of ShaderType 2016-01-26 09:42:49 +01:00
tabbox [tabbox] Expose noModifierGrab to QtQuick 2017-04-12 19:46:48 +02:00
tests Remove KWin::display from kwinglobals 2016-11-16 18:00:00 +01:00
.arcconfig Adding .arcconfig 2016-03-15 13:37:47 +01:00
.reviewboardrc Add reviewboardrc 2014-04-03 10:46:33 +02:00
16-apps-kwin.png Fix installing of icons 2014-06-02 14:56:42 +02:00
32-apps-kwin.png Fix installing of icons 2014-06-02 14:56:42 +02:00
48-apps-kwin.png Fix installing of icons 2014-06-02 14:56:42 +02:00
abstract_client.cpp Desaturate non-responsive windows 2017-04-05 11:16:23 +02:00
abstract_client.h Desaturate non-responsive windows 2017-04-05 11:16:23 +02:00
abstract_egl_backend.cpp Move querying the egl extensions into the AbstractEglBackend 2016-11-17 13:00:29 +01:00
abstract_egl_backend.h Remove epoxy/egl.h from kwinglutils_func.h 2016-11-22 14:21:40 +01:00
activation.cpp Support docks which take input 2016-10-18 08:18:46 +02:00
activities.cpp Revert "Remove saving and loading (and client matching by) WM_COMMAND." 2016-06-23 21:07:03 +02:00
activities.h [autotests/integration] Add a first test case for activities 2016-08-12 12:52:47 +02:00
appmenu.cpp Restore global menu support 2017-01-11 10:21:03 +01:00
appmenu.h Restore global menu support 2017-01-11 10:21:03 +01:00
atoms.cpp Restore global menu support 2017-01-11 10:21:03 +01:00
atoms.h Restore global menu support 2017-01-11 10:21:03 +01:00
client.cpp [KWin Killer] Send short caption to it 2017-04-05 15:31:35 +02:00
client.h support for auto-hidden windows to resize 2017-03-08 23:55:20 +01:00
client_machine.cpp Fix heap-use-after-free use in resolving ClientMachine 2015-10-01 10:09:52 +02:00
client_machine.h Improved resolving whether a window is on local machine 2013-01-21 16:00:49 +01:00
CMakeLists.txt Introduce support for keyboard layout switching policies 2017-04-22 08:15:25 +02:00
COMPLIANCE Fix typo in COMPLIANCE file. 2014-06-20 21:27:12 -03:00
composite.cpp fix uninitialized variable 2017-04-14 15:03:27 +02:00
composite.h [platformx/x11] Add a freeze protection against OpenGL 2016-10-25 09:51:23 +02:00
config-kwin.h.cmake Raise minimum libinput version to 1.2 2016-08-08 09:18:39 +02:00
CONFIGURING
COPYING Put licence files on each repo, removing from root. 2014-03-26 19:01:09 +01:00
COPYING.DOC Put licence files on each repo, removing from root. 2014-03-26 19:01:09 +01:00
cursor.cpp Implement cursor shape tracking on Wayland 2016-10-20 07:52:26 +02:00
cursor.h Implement cursor shape tracking on Wayland 2016-10-20 07:52:26 +02:00
dbusinterface.cpp [kcmkwin/compositing] Hide config options which don't make sense if Compositing is required 2016-09-13 15:47:42 +02:00
dbusinterface.h [kcmkwin/compositing] Hide config options which don't make sense if Compositing is required 2016-09-13 15:47:42 +02:00
debug_console.cpp Replaced InputEventFilter by InputEventSpy in DebugConsole 2017-01-01 19:06:46 +01:00
debug_console.h Replaced InputEventFilter by InputEventSpy in DebugConsole 2017-01-01 19:06:46 +01:00
debug_console.ui Clean up egl/glx extensions in debug console 2016-11-17 13:44:06 +01:00
deleted.cpp Be sure isCurrentTab returns true 2016-06-01 20:46:35 +03:00
deleted.h Remove the unredirect fullscreen windows functionality 2016-08-04 14:48:35 +02:00
effectloader.cpp Introduce an EffectsHandler::animationsSupported -> bool 2016-08-15 17:38:33 +02:00
effectloader.h Ensure that EffectsHandlerImpl::slotClientShown is only invoked once per Window 2016-08-03 16:16:00 +02:00
effects.cpp [effects] Use arg="true" in the kcfg files 2017-04-15 10:03:34 +02:00
effects.h [effects] Use arg="true" in the kcfg files 2017-04-15 10:03:34 +02:00
events.cpp Restore global menu support 2017-01-11 10:21:03 +01:00
ExtraDesktop.sh Add ExtraDestkop.sh files 2011-07-12 16:46:09 +01:00
focuschain.cpp Remove remaining Client usage from FocusChain 2015-05-08 12:43:46 +02:00
focuschain.h Remove remaining Client usage from FocusChain 2015-05-08 12:43:46 +02:00
geometry.cpp Properly implement maximize of ShellClient 2016-11-29 12:35:59 +01:00
geometrytip.cpp Port to CMake AUTOMOC 2016-02-01 21:05:36 +01:00
geometrytip.h Use Xcb::GeometryHints instead of XGetWMNormalHints 2015-01-27 12:48:03 +01:00
gestures.cpp Fix build with clang and GCC6 2017-03-29 14:45:44 +02:00
gestures.h Add support for screenedge touchscreen events through XInput 2.2 2017-03-27 17:44:15 +02:00
globalshortcuts.cpp Add support for global touchpad swipe gestures 2017-03-27 17:43:44 +02:00
globalshortcuts.h Add support for global touchpad swipe gestures 2017-03-27 17:43:44 +02:00
group.cpp Reintroduce nullptr check in Client::removeFromMainClients 2015-09-17 14:17:55 +02:00
group.h Improve updating user timestamp 2014-06-03 13:59:10 +02:00
HACKING HACKING moves to community.kde.org 2011-02-19 17:17:03 +01:00
input.cpp Don't update the focused pointer Surface if a button is pressed 2017-04-20 17:02:42 +02:00
input.h Add support for global touchpad swipe gestures 2017-03-27 17:43:44 +02:00
input_event.cpp Support for relative pointer motion events 2016-10-12 11:26:46 +02:00
input_event.h Add native button to MouseEvent 2016-12-30 19:07:45 +01:00
input_event_spy.cpp It makes sense to actually also build the new input_event_spy.cpp 2016-12-30 19:32:47 +01:00
input_event_spy.h It makes sense to actually also build the new input_event_spy.cpp 2016-12-30 19:32:47 +01:00
keyboard_input.cpp Split KWin::Xkb into a dedicated .h and .cpp 2017-02-15 17:48:55 +01:00
keyboard_input.h Split KWin::Xkb into a dedicated .h and .cpp 2017-02-15 17:48:55 +01:00
keyboard_layout.cpp Introduce support for keyboard layout switching policies 2017-04-22 08:15:25 +02:00
keyboard_layout.h Introduce support for keyboard layout switching policies 2017-04-22 08:15:25 +02:00
keyboard_layout_switching.cpp Introduce support for keyboard layout switching policies 2017-04-22 08:15:25 +02:00
keyboard_layout_switching.h Introduce support for keyboard layout switching policies 2017-04-22 08:15:25 +02:00
keyboard_repeat.cpp Split Keyboard Repeat handling into a dedicated InputEventSpy 2017-01-27 16:03:37 +01:00
keyboard_repeat.h Split Keyboard Repeat handling into a dedicated InputEventSpy 2017-01-27 16:03:37 +01:00
killwindow.cpp Use OnScreenNotification in kill window 2016-12-21 19:45:02 +01:00
killwindow.h Support interactive window selection through the Platform 2016-11-17 08:08:56 +01:00
kwin.kcfg Drop OpenGL based color correction from KWin 2016-11-22 07:16:51 +01:00
kwin.notifyrc SVN_SILENT made messages (.desktop file) - always resolve ours 2017-03-25 06:02:34 +01:00
kwinbindings.cpp Add Quick Tile Window to the Top and Bottom shortcuts 2015-03-31 11:10:13 +02:00
KWinDBusInterfaceConfig.cmake.in Add path to kwin_wayland binary to KWin's installed CMakeConfig 2015-11-19 09:28:16 +01:00
lanczosfilter.cpp Disable lanczos filter with software emulation 2016-08-24 07:49:00 +02:00
lanczosfilter.h Use shader traits API for lanczos filter's shader 2016-01-25 14:11:54 +01:00
layers.cpp Remove non visible internal windows from the x stacking order 2016-09-09 07:41:12 +02:00
logind.cpp Drop not needed include to sys/sysmacros.h from logind.cpp 2016-06-20 11:21:45 +02:00
logind.h Switch virtual teminal through logind seat 2016-04-22 14:18:56 +02:00
main.cpp Provide kxbk config through kwinApp 2017-01-30 17:04:03 +01:00
main.h Provide kxbk config through kwinApp 2017-01-30 17:04:03 +01:00
main_wayland.cpp Require Qt 5.7 and remove pre-5.7 code 2017-02-07 20:43:19 +01:00
main_wayland.h Move everything KCrash related from Application to ApplicationX11 2016-05-09 08:08:49 +02:00
main_x11.cpp Require Qt 5.7 and remove pre-5.7 code 2017-02-07 20:43:19 +01:00
main_x11.h Move everything KCrash related from Application to ApplicationX11 2016-05-09 08:08:49 +02:00
Mainpage.dox
manage.cpp Restore global menu support 2017-01-11 10:21:03 +01:00
Messages.sh killer/ moved to helpers/killer 2016-06-30 11:25:43 +02:00
modifier_only_shortcuts.cpp Track the actual pressed keys in ModifierOnlyShortcuts 2017-02-23 16:55:41 +01:00
modifier_only_shortcuts.h Track the actual pressed keys in ModifierOnlyShortcuts 2017-02-23 16:55:41 +01:00
netinfo.cpp Move skipTaskbar from Client to AbstractClient 2015-06-06 22:11:10 +02:00
netinfo.h [kwin] Remove support for _NET_WM_TAKE_ACTIVITY protocol 2014-03-25 15:03:21 +01:00
onscreennotification.cpp Add support for skip close animation to OnScreenMessage 2017-01-25 13:54:34 +01:00
onscreennotification.h Add support for skip close animation to OnScreenMessage 2017-01-25 13:54:34 +01:00
options.cpp Drop OpenGL based color correction from KWin 2016-11-22 07:16:51 +01:00
options.h Drop OpenGL based color correction from KWin 2016-11-22 07:16:51 +01:00
org.freedesktop.ScreenSaver.xml Add a copy of org.freedesktop.ScreenSaver.xml for KWin 2014-03-24 16:30:22 +01:00
org.kde.kappmenu.xml Restore global menu support 2017-01-11 10:21:03 +01:00
org.kde.kwin.Compositing.xml [kcmkwin/compositing] Hide config options which don't make sense if Compositing is required 2016-09-13 15:47:42 +02:00
org.kde.kwin.Effects.xml [kwin] Add a new EffectLoader 2014-03-28 14:04:55 +01:00
org.kde.KWin.xml Add a debugging console to KWin 2016-03-16 14:30:19 +01:00
osd.cpp Add support for skip close animation to OnScreenMessage 2017-01-25 13:54:34 +01:00
osd.h Add support for skip close animation to OnScreenMessage 2017-01-25 13:54:34 +01:00
outline.cpp Make QmlPath in Outline configurable 2016-01-29 09:50:52 +01:00
outline.h [outline] Use QScopedPointer for created QML item 2014-05-30 15:54:24 +02:00
overlaywindow.cpp Remove displayWidth and displayHeight from the compositor 2014-11-27 09:00:19 +01:00
overlaywindow.h Move glxbackend to x11 standalone plugin 2016-04-15 07:46:02 +02:00
placement.cpp Fix typo 2016-03-03 17:01:52 +01:00
placement.h Move implementation of Client::packTo to AbstractClient 2015-10-26 11:30:34 +01:00
platform.cpp Add support for pointer gestures to nested Wayland platform 2017-03-18 14:39:30 +01:00
platform.h Add support for pointer gestures to nested Wayland platform 2017-03-18 14:39:30 +01:00
pointer_input.cpp Don't update the focused pointer Surface if a button is pressed 2017-04-20 17:02:42 +02:00
pointer_input.h Implement support for pointer constraints 2016-12-08 19:50:24 +01:00
popup_input_filter.cpp Cancel popup if the user clicked window decoration of parent window 2017-04-11 20:22:32 +02:00
popup_input_filter.h Initial support for popup window handling 2017-04-07 16:14:50 +02:00
README
resources.qrc [libkwinglutils] Cleanup Shader API: removal of ShaderType 2016-01-26 09:42:49 +01:00
rules.cpp Match window role in Rules in a case insensitive manner 2016-09-13 08:37:26 +02:00
rules.h [autotests/integration] Add test case for rule matching on window role 2016-08-25 13:23:06 +02:00
sc-apps-kwin.svgz Fix installing of icons 2014-06-02 14:56:42 +02:00
scene.cpp Pass the current output geometry to ScreenPaintData 2016-10-17 09:02:30 +02:00
scene.h Pass the current output geometry to ScreenPaintData 2016-10-17 09:02:30 +02:00
scene_opengl.cpp Drop OpenGL based color correction from KWin 2016-11-22 07:16:51 +01:00
scene_opengl.h Drop OpenGL based color correction from KWin 2016-11-22 07:16:51 +01:00
scene_qpainter.cpp Make WindowPixmap::isValid virtual and override in concrete implementation 2016-09-14 10:23:35 +02:00
scene_qpainter.h Make WindowPixmap::isValid virtual and override in concrete implementation 2016-09-14 10:23:35 +02:00
scene_xrender.cpp SceneXRender::Window uses a static XRenderPicture which it didn't clean up 2016-06-13 15:29:35 +02:00
scene_xrender.h Introduce an EffectsHandler::animationsSupported -> bool 2016-08-15 17:38:33 +02:00
screenedge.cpp Do not handle ScreenEdges::check for Edges which don't activate for Pointer 2017-04-20 17:02:16 +02:00
screenedge.h Add callback functionality for touch screen swipe gestures 2017-04-07 16:16:34 +02:00
screenlockerwatcher.cpp Delay query whether screenlocker is registered till WaylandServer is initialized 2016-08-16 10:17:14 +02:00
screenlockerwatcher.h [autotests/integration] Add ScreenLockerWatcher to the Test::lockScreen and ::unlockScreen 2016-08-16 10:23:37 +02:00
screens.cpp Set initial count of screens before calling Screens::init 2016-08-05 09:59:22 +02:00
screens.h Rename AbstractBackend to Platform 2016-04-07 16:18:12 +02:00
settings.kcfgc Use KConfigXT in KWin::Options 2013-02-14 08:29:03 +01:00
shadow.cpp Ensure to directly delete old Shadow on update 2016-08-18 16:08:42 +02:00
shadow.h [wayland] Shadow gains support for a Wayland protocol 2015-07-15 11:25:16 +02:00
shell_client.cpp Initial support for popup window handling 2017-04-07 16:14:50 +02:00
shell_client.h Initial support for popup window handling 2017-04-07 16:14:50 +02:00
shortcutdialog.ui [kwin] Use ui-file for ShortcutDialog 2014-02-27 10:18:37 +01:00
sm.cpp Drop warning regarding ksmserver in sm.cpp 2016-06-29 11:06:24 +02:00
sm.h Revert "Remove saving and loading (and client matching by) WM_COMMAND." 2016-06-23 21:07:03 +02:00
tabgroup.cpp Workspace::activeClient returns an AbstractClient 2015-05-08 12:43:45 +02:00
tabgroup.h Drop kdecoration.h include from tabgroup.h 2014-12-02 11:48:13 +01:00
thumbnailitem.cpp Make Toplevel::window() no longer virtual and introduce ::windowId() 2016-05-17 14:13:24 +02:00
thumbnailitem.h ThumbnailItem operates on AbstractClient 2015-05-21 13:34:26 +02:00
toplevel.cpp Add support for resize only borders on Wayland 2016-10-05 07:49:23 +02:00
toplevel.h Initial support for popup window handling 2017-04-07 16:14:50 +02:00
touch_input.cpp Add workaround for touch input offset for decorated windows 2017-01-25 13:58:28 +01:00
touch_input.h Pass LibInput::Device* through the event handlers 2016-05-30 15:26:37 +02:00
udev.cpp [platforms/virtual] Use rendernode or vgem device if available for egl 2016-07-21 09:13:57 +02:00
udev.h [platforms/virtual] Use rendernode or vgem device if available for egl 2016-07-21 09:13:57 +02:00
unmanaged.cpp Implement addDamage in Unmanaged 2016-08-12 11:32:48 +02:00
unmanaged.h Implement addDamage in Unmanaged 2016-08-12 11:32:48 +02:00
useractions.cpp remove executable bit from a .cpp file 2017-04-19 12:39:42 +02:00
useractions.h [autotests/integration] Add test case for global shortcuts with Fx 2016-10-05 14:43:38 +02:00
utils.cpp Remove KWin::display from kwinglobals 2016-11-16 18:00:00 +01:00
utils.h Support interactive window selection through the Platform 2016-11-17 08:08:56 +01:00
virtual_terminal.cpp Fix build with future glibc (major/minor macros) 2016-04-20 19:03:34 +02:00
virtual_terminal.h [wayland] Don't break if we try to vt-switch to vt we're on 2015-07-20 11:49:41 +02:00
virtualdesktops.cpp Introduce support for keyboard layout switching policies 2017-04-22 08:15:25 +02:00
virtualdesktops.h Introduce support for keyboard layout switching policies 2017-04-22 08:15:25 +02:00
virtualkeyboard.cpp Require Qt 5.7 and remove pre-5.7 code 2017-02-07 20:43:19 +01:00
virtualkeyboard.h Integrate QtVirtualKeyboard into KWin/Wayland 2016-06-02 11:26:53 +02:00
wayland_cursor_theme.cpp Implement interactive window selection for Wayland platforms 2016-11-17 09:42:12 +01:00
wayland_cursor_theme.h Implement interactive window selection for Wayland platforms 2016-11-17 09:42:12 +01:00
wayland_server.cpp Support creation of PlasmaShellSurface prior to ShellSurface 2017-02-07 19:26:36 +01:00
wayland_server.h Support creation of PlasmaShellSurface prior to ShellSurface 2017-02-07 19:26:36 +01:00
workspace.cpp Restore global menu support 2017-01-11 10:21:03 +01:00
workspace.h Restore global menu support 2017-01-11 10:21:03 +01:00
x11eventfilter.cpp Support multiple event types in X11EventFilter 2016-11-16 07:48:19 +01:00
x11eventfilter.h Support multiple event types in X11EventFilter 2016-11-16 07:48:19 +01:00
xcbutils.cpp Clean debug output 2015-07-20 13:36:27 +02:00
xcbutils.h Fix regression in unit-test introduced with 62b6401175 2015-08-21 11:14:20 +02:00
xkb.cpp Split KWin::Xkb into a dedicated .h and .cpp 2017-02-15 17:48:55 +01:00
xkb.h Split KWin::Xkb into a dedicated .h and .cpp 2017-02-15 17:48:55 +01:00

- A collection of various documents and links related to KWin is at http://techbase.kde.org/Projects/KWin .


- The mailing list for KWin is kwin@kde.org (https://mail.kde.org/mailman/listinfo/kwin).

- If you want to develop KWin, see file HACKING.

- If you want to check KWin's compliance with specifications, see file COMPLIANCE.

- File CONFIGURATION includes some details on configuring KWin.

- Below is some info for application developers about application interaction
  with the window manager, but it'd need some cleanup.








 This README is meant as an explanation of various window manager related
mechanisms that application developers need to be aware of. As some of these
concepts may be difficult to understand for people not having the required
background knowledge (since sometimes it's difficult even for people who
do have the knowledge), the mechanisms are first briefly explained, and
then an example of fixing the various problems is given.

 For comments, questions, suggestions and whatever use the kwin@kde.org
mailing list.


Table of contents:
==================

- Window relations
    - how to make the window manager know which windows belong together
- Focus stealing prevention
    - how to solve cases where focus stealing prevention doesn't work
      properly automatically



Window relations:
=================

(For now, this explanation of window relations is mainly meant for
focus stealing prevention. To be extended later.)

 All windows created by an application should be organized in a tree
with the root being the application's main window. Note that this is about
toplevel windows, not widgets inside the windows. For example, if you
have KWrite running, with a torn-off toolbar (i.e. a standalone toolbar),
a file save dialog open, and the file save dialog showing a dialog
for creating a directory, the window hiearchy should look like this:


             KWrite mainwindow
              /             \
             /               \
      file save dialog      torn-off toolbar
            \
             \
          create directory dialog

 Each subwindow (i.e. all except for the KWrite mainwindow) points to its
main window (which in turn may have another main window, as in the case
of the file save dialog). When the window manager knows these relations,
it can better arrange the windows (keeping subwindows above their
main windows, preventing activation of a main window of a modal dialog,
and similar). Failing to provide this information to the window manager
may have various results, for example having dialogs positioned below
the main window,

The window property used by subwindows to point to their mainwindows is
called WM_TRANSIENT_FOR. It can be seen by running
'xprop | grep WM_TRANSIENT_FOR' and clicking on a window. If the property
is not present, the window does not (claim to) have any mainwindow.
If the property is present, it's value is the window id of its main window;
window id of any window can be found out by running 'xwininfo'. A window
having WM_TRANSIENT_FOR poiting to another window is said to be transient
for that window.

 In some cases, the WM_TRANSIENT_FOR property may not point to any other
existing window, having value of 0, or pointing to the screen number
('xwininfo -root'). These special values mean that the window is transient
for all other windows in its window group. This should be used only
in rare cases, everytime a specific main window is known, WM_TRANSIENT_FOR
should be pointing to it instead of using one of these special values.
(The explanation why is beyond the scope of this document - just accept it
as a fact.)

 With Qt, the WM_TRANSIENT_FOR property is set by Qt automatically, based
on the toplevel widget's parent. If the toplevel widget is of a normal
type (i.e. not a dialog, toolbar, etc.), Qt doesn't set WM_TRANSIENT_FOR
on it. For special widgets, such as dialogs, WM_TRANSIENT_FOR is set
to point to the widget's parent, if it has a specific parent, otherwise
WM_TRANSIENT_FOR points to the root window.

 As already said above, WM_TRANSIENT_FOR poiting to the root window should
be usually avoided, so everytime the widget's main widget is known, the widget
should get it passed as a parent in its constructor.
(TODO KDialog etc. classes should not have a default argument for the parent
argument, and comments like 'just pass 0 as the parent' should go.)



Focus stealing prevention:
==========================

 Since KDE3.2 KWin has a feature called focus stealing prevention. As the name
suggests, it prevents unexpected changes of focus. With older versions of KWin,
if any application opened a new dialog, it became active, and
if the application's main window was on another virtual desktop, also
the virtual desktop was changed. This was annoying, and also sometimes led
to dialogs mistakenly being closed because they received keyboard input that
was meant for the previously active window.

 The basic principle of focus stealing prevention is that the window with most
recent user activity wins. Any window of an application will become active
when being shown only if this application was the most recently used one.
KWin itself, and some of the related kdecore classes should take care
of the common cases, so usually there's no need for any special handling
in applications. Qt/KDE applications, that is. Applications using other
toolkits should in most cases work fine too. If they don't support
the window property _NET_WM_USER_TIME, the window manager may fail to detect
the user timestamp properly, resulting either in other windows becoming active
while the user works with this application, or this application may sometimes
steal focus (this second case should be very rare though).

 There are also cases where KDE applications needs special handling. The two
most common cases are when windows relations are not setup properly to make
KWin realize that they belong to the same application, and when the user
activity is not represented by manipulating with the application windows
themselves.

 Also note that focus stealing prevention implemented in the window manager
can only help with focus stealing between different applications.
If an application itself suddenly pops up a dialog, KWin cannot do anything about
it, and its the application's job to handle this case.


Window relations:
-----------------

 The common case here is when a dialog is shown for an application, but this
dialog is not provided by the application itself, but by some other process.
For example, dialogs with warnings about accepted cookies are provided
by KCookieJar, instead of being shown by Konqueror. In the normal case,
from KWin's point of view the cookie dialog would be an attempt of another
application to show a dialog, and KWin wouldn't allow activation of this
window.

 The solution is to tell the window manager about the relation between
the Konqueror main window and the cookie dialog, by making the dialog
point to the mainwindow. Note that this is not special to focus stealing
prevention, subwindows such as dialogs, toolbars and similar should always
point to their mainwindow. See the section on window relations for full
description.

 The WM_TRANSIENT_FOR property that's set on dialogs to point to their
mainwindow should in the cookie dialog case point to the Konqueror window
for which it has been shown. This is solved in kcookiejar by including
the window id in the DCOP call. When the cookie dialog is shown, its
WM_TRANSIENT_FOR property is manually set using the XSetTransientForHint()
call (see kdelibs/kioslave/http/kcookiejar/kcookiewin.cpp). The arguments
to XSetTransientForHint() call are the X display (i.e. QX11Info::display()),
the window id on which the WM_TRANSIENT_FOR property is to be set
(i.e. use QWidget::winId()), and the window id of the mainwindow.


  Simple short HOWTO:
  
 To put it simply: Let's say you have a daemon application that has
DCOP call "showDialog( QString text )", and when this is called, it shows
a dialog with the given text. This won't work properly with focus stealing
prevention. The DCOP call should be changed to
"showDialog( QString text, long id )". The caller should pass something like
myMainWindow->winId() as the second argument. In the daemon, before
the dialog is shown, a call to XSetTransientHint() should be added:

 XSetTransientForHint( QX11Info::display(), dialog->winId(), id_of_mainwindow );
 
 That's it.

Non-standard user activity:
---------------------------

 The most common case in KDE will be DCOP calls. For example, KDesktop's DCOP
call "KDesktopIface popupExecuteCommand". Executing this DCOP call e.g.
from Konsole as 'dcop kdesktop KDesktopIface popupExecuteCommand" will lead
to showing the minicli, but the last user activity timestamp gained from events
sent by X server will be older than user activity timestamp of Konsole, and
would normally result in minicli not being active. Therefore, before showing
the minicli, kdesktop needs to call KApplication::updateUserTimestamp().

 However, this shouldn't be done with all DCOP calls. If a DCOP call is not
a result of direct user action, calling KApplication::updateUserTimestamp()
would lead to focus stealing. For example, let's assume for a moment
that KMail would use this DCOP call in case it detects the modem is not
connected, allowing to you to start KPPP or whatever tool you use. If KMail
would be configured to check mail every 10 minutes, this would lead to minicli
possibly suddenly showing up at every check. Basically, doing the above change
to kdesktop's minicli means that the popupExecuteCommand() DCOP call is only
for user scripting. (TODO write about focus transferring?)

 Simply said, KApplication::updateUserTimestamp() should be called only
as a result of user action. Unfortunately, I'm not aware of any universal
way how to handle this, so every case will have to be considered separately.