LibGUI: Add highlighting to UrlBox

Author: https://github.com/cammo1123
Commit: cb96c892cc
Pull-request: https://github.com/SerenityOS/serenity/pull/17386
Reviewed-by: https://github.com/AtkinsSJ ✅

Userland/Libraries/LibGUI/TextBox.h

@@ -72,8 +72,11 @@ public:
 private:
     UrlBox();
 
+    void highlight_url();
+
     virtual void mousedown_event(GUI::MouseEvent&) override;
     virtual void focusout_event(GUI::FocusEvent&) override;
+    virtual void focusin_event(GUI::FocusEvent&) override;
 
     bool m_focus_transition { true };
 };