Don't set WindowContextHelpButtonHint by default for dialogs and sheets

This makes the Qt::AA_DisableWindowContextHelpButton flag obsolete. It
is already documented as such in Qt 5, so we can remove it now.

[ChangeLog][QtWidgets] Do not show 'What's this' button anymore in
dialogs on Windows. To show the button again, you need to set
Qt::WindowsContextHelpButtonHint explicitly the top level widget.

Change-Id: I30017ca300441cb2ee37940ce97dfe18eb2b118b
Reviewed-by: Kai Koehne <kai.koehne@qt.io>

3 files changed, 5 insertions, 18 deletions

diff --git a/src/corelib/global/qnamespace.h b/src/corelib/global/qnamespace.h
index ffc3989815..87e5153964 100644
--- a/src/corelib/global/qnamespace.h
+++ b/src/corelib/global/qnamespace.h
@@ -528,7 +528,7 @@ namespace Qt {
         AA_DisableShaderDiskCache = 27,
         AA_DontShowShortcutsInContextMenus = 28,
         AA_CompressTabletEvents = 29,
-        AA_DisableWindowContextHelpButton = 30, // ### Qt 6: remove me
+        // AA_DisableWindowContextHelpButton = 30,
         AA_DisableSessionManager = 31,
 
         // Add new attributes before this line
diff --git a/src/corelib/global/qnamespace.qdoc b/src/corelib/global/qnamespace.qdoc
index cff2fab398..480d96acc7 100644
--- a/src/corelib/global/qnamespace.qdoc
+++ b/src/corelib/global/qnamespace.qdoc
@@ -280,12 +280,6 @@
            \e glProgramBinary(). In the unlikely event of this being problematic,
            set this attribute to disable all disk-based caching of shaders.
 
-    \value AA_DisableWindowContextHelpButton Disables the WindowContextHelpButtonHint
-           by default on Qt::Sheet and Qt::Dialog widgets. This hides the \gui ? button
-           on Windows, which only makes sense if you use \l QWhatsThis functionality.
-           This value was added in Qt 5.10. In Qt 6, WindowContextHelpButtonHint
-           will not be set by default.
-
     \value AA_DisableSessionManager Disables the QSessionManager.
            By default Qt will connect to a running session manager for a GUI
            application on supported platforms, use of a session manager may be
diff --git a/src/widgets/kernel/qwidget.cpp b/src/widgets/kernel/qwidget.cpp
index 7be83c1837..08479a4a37 100644
--- a/src/widgets/kernel/qwidget.cpp
+++ b/src/widgets/kernel/qwidget.cpp
@@ -967,18 +967,11 @@ void QWidgetPrivate::adjustFlags(Qt::WindowFlags &flags, QWidget *w)
         flags |= Qt::WindowSystemMenuHint;
         flags |= Qt::WindowTitleHint;
     }
-    if (customize)
-        ; // don't modify window flags if the user explicitly set them.
-    else if (type == Qt::Dialog || type == Qt::Sheet) {
+    if (!customize) { // don't modify window flags if the user explicitly set them.
         flags |= Qt::WindowTitleHint | Qt::WindowSystemMenuHint | Qt::WindowCloseButtonHint;
-        // ### fixme: Qt 6: Never set Qt::WindowContextHelpButtonHint flag automatically
-        if (!QApplicationPrivate::testAttribute(Qt::AA_DisableWindowContextHelpButton))
-            flags |= Qt::WindowContextHelpButtonHint;
-    } else if (type == Qt::Tool)
-        flags |= Qt::WindowTitleHint | Qt::WindowSystemMenuHint | Qt::WindowCloseButtonHint;
-    else
-        flags |= Qt::WindowTitleHint | Qt::WindowSystemMenuHint | Qt::WindowMinimizeButtonHint |
-                Qt::WindowMaximizeButtonHint | Qt::WindowCloseButtonHint | Qt::WindowFullscreenButtonHint;
+        if (type != Qt::Dialog && type != Qt::Sheet && type != Qt::Tool)
+            flags |= Qt::WindowMinimizeButtonHint | Qt::WindowMaximizeButtonHint | Qt::WindowFullscreenButtonHint;
+    }
     if (w->testAttribute(Qt::WA_TransparentForMouseEvents))
         flags |= Qt::WindowTransparentForInput;
 }