Close splash screen instead of hiding it

With Qt 5, this fixes a bug where (on Linux at least) the entire program
closes if you click the X in the file dialog. 

On Qt 6 things are much more broken without this commit. If the splash
screen is just hidden instead of closed, it keeps the application alive
indefinitely. So we must close the splash screen instead of hiding it to
use the automatic exiting feature. But with the way we were creating the
windows before, the other windows were descendants of the splash screen
for memory management purposes and closing the splash screen would
remove them. So I added a new global object to be the QObject parent for
other top-level windows.

Author: slipher

main.cpp

@@ -216,7 +216,13 @@ int main(int argc, char *argv[])
     engine.addImportPath(QLatin1String("qrc:/"));
     engine.addImageProvider(QLatin1String("fluidicons"), new IconsImageProvider());
     engine.addImageProvider(QLatin1String("fluidicontheme"), new IconThemeImageProvider());
+
+    // Top-level windows can be attached to this so that they aren't QObject-children of the
+    // splash screen. Must destruct before engine.
+    QObject motherOfWindows;
+
     auto* context = engine.rootContext();
+    context->setContextProperty("motherOfWindows", &motherOfWindows);
     context->setContextProperty("updaterSettings", &settings);
     context->setContextProperty("gameLauncher", &gameLauncher);
     context->setContextProperty("splashController", &splashController);

splash.qml

@@ -53,8 +53,9 @@ ApplicationWindow {
 
     function showUpdater() {
         splashDownloaderConnections.enabled = false;
-        updaterWindowLoader.active = true
-        splash.hide();
+        var mainWindowComponent = Qt.createComponent("main.qml");
+        mainWindowComponent.createObject(motherOfWindows);
+        splash.close();
     }
 
     Connections {
@@ -96,10 +97,8 @@ ApplicationWindow {
         target: downloader
 
         function onFatalMessage(message) {
-            updateFailed.errorDetail = message;
-            updateFailedWindow.show();
-            updateFailed.open();
-            splash.hide();
+            updateFailedComponent.createObject(motherOfWindows, { errorDetail: message });
+            splash.close();
         }
     }
 
@@ -166,15 +165,10 @@ ApplicationWindow {
         Material.accent: Material.Teal
     }
 
-    Loader {
-        id: updaterWindowLoader
-        active: false
-        source: "qrc:/main.qml"
-    }
+    property Component updateFailedComponent: ApplicationWindow {
+        property alias errorDetail: updateFailed.errorDetail
 
-    ApplicationWindow {
-        id: updateFailedWindow
-        visible: false
+        visible: true
         width: updateFailed.width
         height: updateFailed.height
         maximumWidth: updateFailed.width
@@ -183,5 +177,6 @@ ApplicationWindow {
             id: updateFailed
             failedOperation: 'Launcher self-update'
         }
+        Component.onCompleted: updateFailed.open()
     }
 }