add ppbr export dialog, implement text input focus

src/node_text_input.h

@@ -8,6 +8,7 @@ public:
     float timer = 0;
     NodeText* m_text;
     NodeBorder* m_cursor;
+    NodeBorder* m_border;
     std::string m_string;
     std::function<void(NodeTextInput*target)> on_return;
     virtual Node* clone_instantiate() const override;