fix search bar bad reset

Clear the search bar only if the focus is due to a mouse click

src/searchbar.cpp

@@ -2,6 +2,7 @@
 
 #include <QCompleter>
 #include <QTimer>
+#include <QFocusEvent>
 
 #include "kiwixapp.h"
 
@@ -82,6 +83,7 @@ void SearchBar::on_currentTitleChanged(const QString& title)
 
 void SearchBar::focusInEvent( QFocusEvent* event)
 {
+    if (event->reason() == Qt::MouseFocusReason)
         clear();
     QLineEdit::focusInEvent(event);
     m_button.set_searchMode(true);