Update Qt Designer documentation.

- Document new QUiPlugin module.
- Fix example documentation to reflect the changes in
  the qmake variables (QT/CONFIG).

Task-number: QTBUG-44724
Change-Id: Idd85d601295af25d634c3186e993abc7090fe002
Reviewed-by: Oswald Buddenhagen <oswald.buddenhagen@theqtcompany.com>

4 files changed, 33 insertions, 75 deletions

diff --git a/examples/designer/doc/src/containerextension.qdoc b/examples/designer/doc/src/containerextension.qdoc
index 4329d90a5..f82e1c042 100644
--- a/examples/designer/doc/src/containerextension.qdoc
+++ b/examples/designer/doc/src/containerextension.qdoc
@@ -107,24 +107,12 @@
     recognized as a plugin by Qt by using the Q_PLUGIN_METADATA() macro
     to export the relevant widget information.
 
-    The \c CONFIG variable contains two values, \c designer and \c
-    plugin:
+    The \c CONFIG variable is set to \c plugin, which ensures that \c qmake
+    considers the custom widget a plugin library.
 
-    \list
-        \li \c designer: Since custom widgets plugins rely on components
-           supplied with \QD, this value ensures that our plugin links against
-           \QD's library (\c libQtDesigner.so).
-
-        \li \c plugin: We also need to ensure that \c qmake considers the
-           custom widget a \e plugin library.
-    \endlist
-
-    When Qt is configured to build in both debug and release modes,
-    \QD will be built in release mode.  When this occurs, it is
-    necessary to ensure that plugins are also built in release
-    mode. For that reason we add a \c debug_and_release value to the
-    \c CONFIG variable. Otherwise, if a plugin is built in a mode that
-    is incompatible with \QD, it won't be loaded and installed.
+    The \c QT variable contains the value \c designer. Since the plugin uses
+    components supplied with \QD that require linkage, this value ensures
+    that our plugin links against \QD's library (\c libQtDesigner.so).
 
     The header and source files for the widget are declared in the
     usual way:
diff --git a/examples/designer/doc/src/customwidgetplugin.qdoc b/examples/designer/doc/src/customwidgetplugin.qdoc
index 84da3c495..2c3c9c6df 100644
--- a/examples/designer/doc/src/customwidgetplugin.qdoc
+++ b/examples/designer/doc/src/customwidgetplugin.qdoc
@@ -57,27 +57,18 @@
     recognized as a plugin by Qt by using the Q_PLUGIN_METADATA() macro
     to export the relevant widget information.
 
-    The \c CONFIG variable contains two values, \c designer and \c
-    plugin:
 
-    \list
-
-    \li \c designer: Since custom widgets plugins rely on components
-    supplied with \QD, this value ensures that our plugin links
-    against \QD's library (\c libQtDesigner.so).
-
-    \li \c plugin: We also need to ensure that \c qmake considers the
-    custom widget a plugin library.
-
-    \endlist
-
-    When Qt is configured to build in both debug and release modes,
-    \QD will be built in release mode. When this occurs, it is
-    necessary to ensure that plugins are also built in release
-    mode. For that reason we add the \c debug_and_release value to the
-    \c CONFIG variable. Otherwise, if a plugin is built in a mode that
-    is incompatible with \QD, it won't be loaded and
-    installed.
+    The \c CONFIG variable is set to \c plugin, which ensures that \c qmake
+    considers the custom widget a plugin library.
+
+    The \c QT variable contains the keyword \c uiplugin. This plugin type
+    provides a factory function for custom widget creation by implementing
+    the abstract interfaces QDesignerCustomWidgetInterface or
+    QDesignerCustomWidgetCollectionInterface, suitable for use with
+    QUiLoader. It does not have a dependency on the \QD libraries.
+    Plugins accessing other interfaces of \QD to implement container extensions
+    or other \QD specific functionality follow different rules and are covered
+    by other examples.
 
     The header and source files for the widget are declared in the usual way,
     and we provide an implementation of the plugin interface so that \QD can
diff --git a/examples/designer/doc/src/taskmenuextension.qdoc b/examples/designer/doc/src/taskmenuextension.qdoc
index 541e2a3ed..5f223f353 100644
--- a/examples/designer/doc/src/taskmenuextension.qdoc
+++ b/examples/designer/doc/src/taskmenuextension.qdoc
@@ -108,25 +108,12 @@
     recognized as a plugin by Qt by using the Q_PLUGIN_METADATA() macro to
     export the relevant widget information.
 
-    The \c CONFIG variable contains two values, \c designer and \c
-    plugin:
+    The \c CONFIG variable is set to \c plugin, which ensures that \c qmake
+    considers the custom widget a plugin library.
 
-    \list
-        \li \c designer: Since custom widgets plugins rely on components
-           supplied with \QD, this value ensures that our plugin links against
-           \QD's library (\c libQtDesigner.so).
-
-        \li \c plugin: We also need to ensure that \c qmake considers the
-           custom widget a \e plugin library.
-    \endlist
-
-    When Qt is configured to build in both debug and release modes,
-    \QD will be built in release mode.  When this occurs, it is
-    necessary to ensure that plugins are also built in release
-    mode. For that reason we add the \c debug_and_release value to
-    the \c CONFIG variable. Otherwise, if a plugin is built in a mode
-    that is incompatible with \QD, it won't be loaded and
-    installed.
+    The \c QT variable contains the value \c designer. Since the plugin uses
+    components supplied with \QD that require linkage, this value ensures
+    that our plugin links against \QD's library (\c libQtDesigner.so).
 
     The header and source files for the widget are declared in the
     usual way:
diff --git a/examples/designer/doc/src/worldtimeclockplugin.qdoc b/examples/designer/doc/src/worldtimeclockplugin.qdoc
index bc45a751a..917ab8bda 100644
--- a/examples/designer/doc/src/worldtimeclockplugin.qdoc
+++ b/examples/designer/doc/src/worldtimeclockplugin.qdoc
@@ -145,26 +145,18 @@
     \snippet worldtimeclockplugin/worldtimeclockplugin.pro 0
     \snippet worldtimeclockplugin/worldtimeclockplugin.pro 1
 
-    The \c TEMPLATE variable's value make \c qmake create the custom
-    widget as a library. The \c CONFIG variable contains two values,
-    \c designer and \c plugin:
-
-    \list
-        \li \c designer: Since custom widgets plugins rely on components
-           supplied with \QD, this value ensures that our plugin links against
-           \QD's library (\c libQtDesigner.so).
-
-        \li \c plugin: We also need to ensure that \c qmake considers the
-           custom widget a \e plugin library.
-    \endlist
-
-    When Qt is configured to build in both debug and release modes,
-    \QD will be built in release mode.  When this occurs, it is
-    necessary to ensure that plugins are also built in release
-    mode. For that reason you might have to add a \c release value to
-    your \c CONFIG variable. Otherwise, if a plugin is built in a mode
-    that is incompatible with \QD, it won't be loaded and
-    installed.
+    The \c TEMPLATE variable's value in conjunction with the keyword
+    \c plugin in the \c CONFIG variable make \c qmake create the custom
+    widget as a plugin library.
+
+    The \c QT variable contains the keyword \c uiplugin. This plugin type
+    provides a factory function for custom widget creation by implementing
+    the abstract interfaces QDesignerCustomWidgetInterface or
+    QDesignerCustomWidgetCollectionInterface, suitable for use with
+    QUiLoader. It does not have a dependency on the \QD libraries.
+    Plugins accessing other interfaces of \QD to implement container extensions
+    or other \QD specific functionality follow different rules and are covered
+    by other examples.
 
     The header and source files for the widget are declared in the
     usual way, and in addition we provide an implementation of the