Pass the mainWindow as parent for the fileOpenDialog.

kiwixapp.h

@@ -20,6 +20,7 @@ public:
     KiwixSchemeHandler* getSchemeHandler() { return &schemeHandler; }
     KiwixRequestInterceptor* getRequestInterceptor() { return &requestIntercetor; }
     Library* getLibrary() { return &library; }
+    MainWindow* getMainWindow() { return mainWindow; }
 private:
     Library library;
     MainWindow* mainWindow;

main.cpp

@@ -16,7 +16,7 @@ int main(int argc, char *argv[])
     QString zimfile;
     auto positionalArguments = parser.positionalArguments();
     if (positionalArguments.size() < 1){
-        zimfile = QFileDialog::getOpenFileName(nullptr,
+        zimfile = QFileDialog::getOpenFileName(a.getMainWindow(),
             "Open Zim",
             QString(),
             "ZimFile (*.zim*)");