NOISSUE add hack for system themes. Maybe it works?

application/MultiMC.cpp

@@ -355,7 +355,7 @@ MultiMC::MultiMC(int &argc, char **argv) : QApplication(argc, argv)
 	connect(this, SIGNAL(aboutToQuit()), SLOT(onExit()));
 
 	setIconTheme(settings()->get("IconTheme").toString());
-	//setApplicationTheme(settings()->get("ApplicationTheme").toString());
+	setApplicationTheme(settings()->get("ApplicationTheme").toString());
 
 	initAnalytics();
 
@@ -876,9 +876,19 @@ void MultiMC::setApplicationTheme(const QString& name)
 	{
 		auto & theme = (*themeIter).second;
 		setStyle(QStyleFactory::create(theme->qtTheme()));
-		setPalette(theme->colorScheme());
+		if(theme->hasColorScheme())
+		{
+			setPalette(theme->colorScheme());
+		}
+		if(theme->hasStyleSheet())
+		{
+			setStyleSheet(theme->appStyleSheet());
+		}
+		else
+		{
+			setStyleSheet(QString());
+		}
 		QDir::setSearchPaths("theme", theme->searchPaths());
-		setStyleSheet(theme->appStyleSheet());
 	}
 	else
 	{

application/themes/BrightTheme.cpp

@@ -10,6 +10,11 @@ QString BrightTheme::name()
 	return QObject::tr("Bright");
 }
 
+bool BrightTheme::hasColorScheme()
+{
+	return true;
+}
+
 QPalette BrightTheme::colorScheme()
 {
 	QPalette brightPalette;
@@ -39,6 +44,11 @@ QColor BrightTheme::fadeColor()
 	return QColor(239,240,241);
 }
 
+bool BrightTheme::hasStyleSheet()
+{
+	return false;
+}
+
 QString BrightTheme::appStyleSheet()
 {
 	return QString();

application/themes/BrightTheme.h

@@ -9,7 +9,9 @@ public:
 
 	QString id() override;
 	QString name() override;
+	bool hasStyleSheet() override;
 	QString appStyleSheet() override;
+	bool hasColorScheme() override;
 	QPalette colorScheme() override;
 	double fadeAmount() override;
 	QColor fadeColor() override;

application/themes/CustomTheme.cpp

@@ -208,11 +208,21 @@ QString CustomTheme::name()
 	return m_name;
 }
 
+bool CustomTheme::hasColorScheme()
+{
+	return true;
+}
+
 QPalette CustomTheme::colorScheme()
 {
 	return m_palette;
 }
 
+bool CustomTheme::hasStyleSheet()
+{
+	return true;
+}
+
 QString CustomTheme::appStyleSheet()
 {
 	return m_styleSheet;

application/themes/CustomTheme.h

@@ -10,7 +10,9 @@ public:
 
 	QString id() override;
 	QString name() override;
+	bool hasStyleSheet() override;
 	QString appStyleSheet() override;
+	bool hasColorScheme() override;
 	QPalette colorScheme() override;
 	double fadeAmount() override;
 	QColor fadeColor() override;

application/themes/DarkTheme.cpp

@@ -10,6 +10,11 @@ QString DarkTheme::name()
 	return QObject::tr("Dark");
 }
 
+bool DarkTheme::hasColorScheme()
+{
+	return true;
+}
+
 QPalette DarkTheme::colorScheme()
 {
 	QPalette darkPalette;
@@ -39,6 +44,11 @@ QColor DarkTheme::fadeColor()
 	return QColor(49,54,59);
 }
 
+bool DarkTheme::hasStyleSheet()
+{
+	return true;
+}
+
 QString DarkTheme::appStyleSheet()
 {
 	return "QToolTip { color: #ffffff; background-color: #2a82da; border: 1px solid white; }";

application/themes/DarkTheme.h

@@ -9,7 +9,9 @@ public:
 
 	QString id() override;
 	QString name() override;
+	bool hasStyleSheet() override;
 	QString appStyleSheet() override;
+	bool hasColorScheme() override;
 	QPalette colorScheme() override;
 	double fadeAmount() override;
 	QColor fadeColor() override;

application/themes/ITheme.h

@@ -2,14 +2,18 @@
 #include <QString>
 #include <QPalette>
 
+class QStyle;
+
 class ITheme
 {
 public:
 	virtual ~ITheme() {}
 	virtual QString id() = 0;
 	virtual QString name() = 0;
+	virtual bool hasStyleSheet() = 0;
 	virtual QString appStyleSheet() = 0;
 	virtual QString qtTheme() = 0;
+	virtual bool hasColorScheme() = 0;
 	virtual QPalette colorScheme() = 0;
 	virtual QColor fadeColor() = 0;
 	virtual double fadeAmount() = 0;

application/themes/SystemTheme.cpp

@@ -21,6 +21,7 @@ SystemTheme::SystemTheme()
 	}
 	// fall back to fusion if we can't find the current theme.
 	systemTheme = "Fusion";
+	qWarning() << "System theme not found, defaulted to Fusion";
 }
 
 QString SystemTheme::id()
@@ -57,3 +58,18 @@ QColor SystemTheme::fadeColor()
 	{
 		return QColor(128,128,128);
 	}
+
+bool SystemTheme::hasStyleSheet()
+{
+	return false;
+}
+
+bool SystemTheme::hasColorScheme()
+{
+	// FIXME: horrible hack to work around Qt's sketchy theming APIs
+#if defined(Q_OS_LINUX)
+	return true;
+#else
+	return false;
+#endif
+}

application/themes/SystemTheme.h

@@ -11,7 +11,9 @@ public:
 	QString id() override;
 	QString name() override;
 	QString qtTheme() override;
+	bool hasStyleSheet() override;
 	QString appStyleSheet() override;
+	bool hasColorScheme() override;
 	QPalette colorScheme() override;
 	double fadeAmount() override;
 	QColor fadeColor() override;