LibGUI: Invalidate GroupBox layout on font change

Userland/Libraries/LibGUI/GroupBox.cpp

@@ -52,6 +52,12 @@ void GroupBox::paint_event(PaintEvent& event)
     }
 }
 
+void GroupBox::fonts_change_event(FontsChangeEvent& event)
+{
+    Widget::fonts_change_event(event);
+    invalidate_layout();
+}
+
 void GroupBox::set_title(const StringView& title)
 {
     if (m_title == title)

Userland/Libraries/LibGUI/GroupBox.h

@@ -23,6 +23,7 @@ protected:
     explicit GroupBox(const StringView& title = {});
 
     virtual void paint_event(PaintEvent&) override;
+    virtual void fonts_change_event(FontsChangeEvent&) override;
 
 private:
     String m_title;