searchengine: don't use strings to determine the status of search processes

'&' symbols are dynamically added to strings, making comparisons
unreliable.

src/searchengine/searchengine.cpp

@@ -183,6 +183,7 @@ void SearchEngine::searchTextEdited(QString)
 {
     // Enable search button
     search_button->setText(tr("Search"));
+    newQueryString = true;
 }
 
 void SearchEngine::giveFocusToSearchInput()
@@ -210,12 +211,14 @@ void SearchEngine::on_search_button_clicked()
 
         searchProcess->waitForFinished(1000);
 
-        if (search_button->text() != tr("Search")) {
+        if (!newQueryString) {
             search_button->setText(tr("Search"));
             return;
         }
     }
 
+    newQueryString = false;
+
     // Reload environment variables (proxy)
     searchProcess->setEnvironment(QProcess::systemEnvironment());
 

src/searchengine/searchengine.h

@@ -126,6 +126,7 @@ private:
     QList<QPointer<SearchTab> > all_tab; // To store all tabs
     const SearchCategories full_cat_names;
     MainWindow *mp_mainWindow;
+    bool newQueryString;
 };
 
 #endif