fix(Settings/LanguageView): do not change language on the fly

disable retranslation, display a confirmation dialog and apply the
language change after app restart

rationale: the way the retranslation works internally is that it force
reevaluation of _all_ QML bindings which:
- might lead to crashes (immediately or later)
- lots of warnings printed to console, some bindings can get broken as a result
- not all UI is correctly retranslated on the fly (we have lots of places
where we assign the text imperatively via JS code), so these wouldn't
appear translated before app restart anyway

Fixes #7823

src/app_service/service/language/service.nim

@@ -28,7 +28,7 @@ proc delete*(self: Service) =
 proc newService*(events: EventEmitter): Service =
   result = Service()
   result.events = events
-  result.shouldRetranslate = false #not defined(linux)
+  result.shouldRetranslate = false
 
 proc obtainLanguages(dir: string): seq[string] =
   let localeRe = re".*qml_(.*).qm"

ui/app/AppLayouts/Profile/views/LanguageView.qml

@@ -39,7 +39,7 @@ SettingsContentBase {
 
     function changeLanguage(key) {
         languagePicker.newKey = key
-        languagePause.start()
+        Qt.callLater(root.languageStore.changeLanguage, languagePicker.newKey)
     }
 
     ColumnLayout {
@@ -105,14 +105,6 @@ SettingsContentBase {
                     return ""
                 }
 
-                Timer {
-                    id: languagePause
-                    interval: 100
-                    onTriggered: {
-                        // changeLanguage function operation blocks a little bit the UI so getting around it with a small pause (timer) in order to get the desired visual behavior
-                        root.languageStore.changeLanguage(languagePicker.newKey)
-                    }
-                }
                 objectName: "languagePicker"
                 inputList: SortFilterProxyModel {
                     sourceModel: root.languageStore.languageModel
@@ -154,18 +146,9 @@ SettingsContentBase {
 
                 onItemPickerChanged: {
                     if(selected && root.languageStore.currentLanguage !== key) {
-                        // IMPORTANT: Workaround to temporary resolve the crash we have when language is changed (`startupModule` is null and some qml bindings are still calling this dead pointer) so, change language will not retranslate
-                        // and instead, also on mac and win, the app will quit to apply the new language
-                        // TEMPORARY: It should be removed as it is only used in Linux OS but it must be investigated how to change language in execution time, as well, in Linux (will be addressed in another task)
-                        //if (Qt.platform.os === Constants.linux) {
-                            root.changeLanguage(key)
-                            linuxConfirmationDialog.active = true
-                            linuxConfirmationDialog.item.open()
-                        // }
-
-                        //else {
-                        //    root.changeLanguage(key)
-                        //}
+                        root.changeLanguage(key)
+                        languageConfirmationDialog.active = true
+                        languageConfirmationDialog.item.open()
                     }
                 }
             }
@@ -206,16 +189,15 @@ SettingsContentBase {
             }
         }
 
-        // TEMPORARY: It should be removed as it is only used in Linux OS but it must be investigated how to change language in execution time, as well, in Linux (will be addressed in another task)
         Loader {
-            id: linuxConfirmationDialog
+            id: languageConfirmationDialog
             active: false
             sourceComponent: ConfirmationDialog {
                 header.title: qsTr("Change language")
                 confirmationText: qsTr("Display language has been changed. You must restart the application for changes to take effect.")
                 confirmButtonLabel: qsTr("Close the app now")
                 onConfirmButtonClicked: {
-                    linuxConfirmationDialog.active = false
+                    languageConfirmationDialog.active = false
                     Qt.quit()
                 }
             }

vendor/DOtherSide/lib/src/DOtherSide.cpp

@@ -439,7 +439,8 @@ void dos_qguiapplication_load_translation(::DosQQmlApplicationEngine *vptr, cons
     if (g_translator.load(translationPackage)) {
         bool success = QGuiApplication::installTranslator(&g_translator);
         auto engine = static_cast<QQmlApplicationEngine *>(vptr);
-        if (shouldRetranslate) engine->retranslate();
+        if (engine && success && shouldRetranslate)
+            engine->retranslate();
     } else {
         printf("Failed to load translation file %s\n", translationPackage);
     }