Update text boxes in the inner fixed-timestep loop

So they don't go really quickly.

desktop_version/src/Graphics.h

@@ -97,6 +97,7 @@ public:
 
 	void drawimagecol(int t, int xp, int yp, int r, int g, int b, bool cent= false);
 
+	void updatetextboxes();
 	void drawgui();
 
 	void drawsprite(int x, int y, int t, int r, int g, int b);