Fix Style Plugin Example, and add some CMake Docs

A few things:

- Improved the documentation by adding a CMake section, briefly
  describing the process of adding the plugin, and placing it where it
  should be.
- Write a note about the case where the style may be overwritten at
  launch, and how to set the a new style using a CLI
- Improved the CMake build such that it creates the App Bundle
  correctly, and also works without an App Bundle as well.
- Changed the example, and plugin such that now instead of a QPushButton
  we have a QTextEdit, and change the text color.
- Replaced the application screenshot

Fixes: QTBUG-107842
Fixes: QTBUG-109227
Change-Id: I161a91b27df016ff6230fac3871b79d2dfbdf18a
Reviewed-by: Alexandru Croitor <alexandru.croitor@qt.io>

1 files changed, 11 insertions, 1 deletions

diff --git a/examples/widgets/tools/styleplugin/plugin/plugin.pro b/examples/widgets/tools/styleplugin/plugin/plugin.pro
index 35184fc82a..5ab00016ca 100644
--- a/examples/widgets/tools/styleplugin/plugin/plugin.pro
+++ b/examples/widgets/tools/styleplugin/plugin/plugin.pro
@@ -12,7 +12,17 @@ win32 {
     CONFIG(debug, release|debug):DESTDIR = ../debug/styles/
     CONFIG(release, release|debug):DESTDIR = ../release/styles/
 } else {
-    DESTDIR = ../styles/
+    macos {
+        # The non-app-bundle case is not supported with qmake, because
+        # the plugin project cannot know whether the app is built
+        # as a bundle or not.
+        DESTDIR = ../styleplugin.app/Contents/PlugIns/styles/
+        contains(QT_CONFIG, debug) {
+            TARGET = $$join(TARGET,,,_debug)
+        }
+    } else {
+        DESTDIR = ../styles/
+    }
 }
 
 EXAMPLE_FILES += simplestyle.json