Compatibility with older Qt versions

Attorney_Online_remake.pro

@@ -82,6 +82,8 @@ unix:LIBS += -L$$PWD -lbass
 win32:LIBS += "$$PWD/bass.dll"
 android:LIBS += -L$$PWD\android\libs\armeabi-v7a\ -lbass
 
+CONFIG += c++11
+
 ANDROID_PACKAGE_SOURCE_DIR = $$PWD/android
 
 RESOURCES += \

main.cpp

@@ -10,7 +10,12 @@
 
 int main(int argc, char *argv[])
 {
+#if QT_VERSION > QT_VERSION_CHECK(5, 6, 0)
+    // High-DPI support is for Qt version >=5.6.
+    // However, many Linux distros still haven't brought their stable/LTS
+    // packages up to Qt 5.6, so this is conditional.
     AOApplication::setAttribute(Qt::AA_EnableHighDpiScaling);
+#endif
     AOApplication main_app(argc, argv);
     main_app.construct_lobby();
     main_app.net_manager->connect_to_master();