diff --git a/include/render.h b/include/render.h
index e7a0b840..7dd2d226 100644
--- a/include/render.h
+++ b/include/render.h
@@ -29,12 +29,13 @@ enum {
 	DoubleBoth=		0x03
 };
 
-bool RENDER_StartUpdate(void);
 
-void RENDER_EndUpdate(void);
 
-void RENDER_Part(Bit8u * data,Bitu x,Bitu y,Bitu dx,Bitu dy);
+typedef void (* RENDER_Part_Handler)(Bit8u * src,Bitu x,Bitu y,Bitu dx,Bitu dy);
+typedef void (* RENDER_Draw_Handler)(RENDER_Part_Handler part_handler);
 
-void RENDER_SetSize(Bitu width,Bitu height,Bitu bpp,Bitu pitch,float ratio,Bitu flags);
+void RENDER_DoUpdate(void);
+
+void RENDER_SetSize(Bitu width,Bitu height,Bitu bpp,Bitu pitch,float ratio,Bitu flags,RENDER_Draw_Handler draw_handler);
 
 void RENDER_SetPal(Bit8u entry,Bit8u red,Bit8u green,Bit8u blue);
diff --git a/include/video.h b/include/video.h
index d6424129..63d952ec 100644
--- a/include/video.h
+++ b/include/video.h
@@ -22,6 +22,8 @@
 
 typedef void (* GFX_ModeCallBack)(Bitu width,Bitu height,Bitu bpp,Bitu pitch,Bitu flags);
 
+typedef void (* GFX_DrawCallBack)(void * data);
+
 struct GFX_PalEntry {
 	Bit8u r;
 	Bit8u g;
@@ -40,14 +42,13 @@ void GFX_Events(void);
 void GFX_SetPalette(Bitu start,Bitu count,GFX_PalEntry * entries);
 
 Bitu GFX_GetRGB(Bit8u red,Bit8u green,Bit8u blue);
-void GFX_SetSize(Bitu width,Bitu height,Bitu bpp,Bitu flags,GFX_ModeCallBack callback);
+void GFX_SetSize(Bitu width,Bitu height,Bitu bpp,Bitu flags,GFX_ModeCallBack mode_callback, GFX_DrawCallBack draw_callback);
 
 void GFX_Start(void);
 void GFX_Stop(void);
 void GFX_SwitchFullScreen(void);
 
-void * GFX_StartUpdate(void);
-void GFX_EndUpdate(void);
+void GFX_DoUpdate(void);
 
 #endif