Index: gui/primitive.c
===================================================================
--- gui/primitive.c	(revision 8036)
+++ gui/primitive.c	(working copy)
@@ -999,6 +999,7 @@
 	AG_Widget *wid = p;
 	int x, y;
 
+	SDL_LockSurface(agView->v);
 	for (y = 0; y < r.h; y++) {
 		for (x = 0; x < r.w; x++) {
 			AG_BLEND_RGBA2_CLIPPED(agView->v,
@@ -1008,6 +1009,7 @@
 			    func);
 		}
 	}
+	SDL_UnlockSurface(agView->v);
 }
 
 /* Render a gimp-style background tiling. */
Index: gui/widget.h
===================================================================
--- gui/widget.h	(revision 8094)
+++ gui/widget.h	(working copy)
@@ -279,8 +279,11 @@
 		AG_WidgetPutPixel32_GL(p, vx,vy, color);
 	} else
 #endif
-	if (!AG_CLIPPED_PIXEL(agView->v, vx,vy))
+	if (!AG_CLIPPED_PIXEL(agView->v, vx,vy)) {
+		SDL_LockSurface(agView->v);
 		AG_PUT_PIXEL2(agView->v, vx,vy, color);
+		SDL_UnlockSurface(agView->v);
+	}
 }
 
 static __inline__ void
@@ -295,8 +298,11 @@
 		AG_WidgetPutPixelRGB_GL(p, vx,vy, r,g,b);
 	} else
 #endif
-	if (!AG_CLIPPED_PIXEL(agView->v, vx, vy))
+	if (!AG_CLIPPED_PIXEL(agView->v, vx, vy)) {
+		SDL_LockSurface(agView->v);
 		AG_PUT_PIXEL2(agView->v, vx,vy, AG_MapRGB(agVideoFmt,r,g,b));
+		SDL_UnlockSurface(agView->v);
+	}
 }
 
 static __inline__ void