1 files changed, 2 insertions, 0 deletions
diff --git a/src/Screen.h b/src/Screen.h
index 950aab4..346d04d 100644
--- a/src/Screen.h
+++ b/src/Screen.h
@@ -2,6 +2,7 @@
 #define SG_SCREEN
 
 #include <ostream>
+#include <string>
 
 typedef unsigned int mm;
 
@@ -19,6 +20,7 @@ protected:
 	mm height;
 
 	Screen(mm width, mm height);
+	virtual std::string extraOutput() const = 0;
 };
 
 std::ostream& operator<<(std::ostream& ostr, const Screen& screen);