Revert "Let styles indicate that they support dark mode"

This reverts commit 3ee7a9f85c.

Styles that don't support dark mode can overwrite the palette in
a QStyle::polish(QPalette &) override instead.

Change-Id: I8b84d822d91be5b3f67f76f791a1330bba7ea546
Reviewed-by: Tor Arne Vestbø <tor.arne.vestbo@qt.io>
Reviewed-by: Santhosh Kumar <santhosh.kumar.selvaraj@qt.io>

src/plugins/styles/mac/qmacstyle_mac.mm

@@ -2892,9 +2892,6 @@ int QMacStyle::styleHint(StyleHint sh, const QStyleOption *opt, const QWidget *w
     case SH_TabBar_AllowWheelScrolling:
         ret = false;
         break;
-    case SH_SupportsDarkAppearance:
-        ret = true;
-        break;
     default:
         ret = QCommonStyle::styleHint(sh, opt, w, hret);
         break;

src/plugins/styles/windowsvista/qwindowsvistastyle.cpp

@@ -2316,10 +2316,6 @@ int QWindowsVistaStyle::styleHint(StyleHint hint, const QStyleOption *option, co
         ret = 1;
         break;
 
-    case SH_SupportsDarkAppearance:
-        ret = 0;
-        break;
-
     default:
         ret = QWindowsStyle::styleHint(hint, option, widget, returnData);
         break;

src/widgets/styles/qcommonstyle.cpp

@@ -5407,7 +5407,6 @@ int QCommonStyle::styleHint(StyleHint sh, const QStyleOption *opt, const QWidget
     case SH_ItemView_PaintAlternatingRowColorsForEmptyArea:
     case SH_ComboBox_UseNativePopup:
     case SH_Table_AlwaysDrawLeftTopGridLines:
-    case SH_SupportsDarkAppearance:
         ret = false;
         break;
     case SH_MenuBar_AltKeyNavigation:

src/widgets/styles/qfusionstyle.cpp

@@ -3630,7 +3630,6 @@ int QFusionStyle::styleHint(StyleHint hint, const QStyleOption *option, const QW
     case SH_MenuBar_MouseTracking:
     case SH_Menu_MouseTracking:
     case SH_Menu_SupportsSections:
-    case SH_SupportsDarkAppearance:
         return 1;
 
 #if defined(QT_PLATFORM_UIKIT)

src/widgets/styles/qstyle.cpp

@@ -1987,13 +1987,6 @@ void QStyle::drawItemPixmap(QPainter *painter, const QRect &rect, int alignment,
            not when the header is hidden. Defaults to false.
            This enum value has been introduced in Qt 6.3.
 
-    \value SH_SupportsDarkAppearance
-           Determines whether the style is able to render a UI correctly with
-           a dark palette. Defaults to false. Style implementors should return true
-           if they have tested the style with a palette where the background colors
-           are darker than the foreground colors.
-           This enum value has been introduced in Qt 6.5.
-
     \sa styleHint()
 */
 

src/widgets/styles/qstyle.h

@@ -702,7 +702,6 @@ public:
         SH_TabBar_AllowWheelScrolling,
         SH_Table_AlwaysDrawLeftTopGridLines,
         SH_SpinBox_SelectOnStep,
-        SH_SupportsDarkAppearance,
         // Add new style hint values here
 
         SH_CustomBase = 0xf0000000