Add Keyboard input and enter support for text editor.

src/ui_elements/widgets/Widget.h

@@ -1,6 +1,7 @@
 #pragma once
 
 #include "DiscretePoint.h"
+#include "FontItem.h"
 #include "Color.h"
 
 #include <memory>
@@ -149,6 +150,8 @@ protected:
 
     std::string mName;
     std::vector<TransformNode*> mPendingChildNodes;
+
+    FontItem mDefaultFont;
 };
 
 using WidgetUPtr = std::unique_ptr<Widget>;