--- rxvt-unicode/src/background.C	2012/04/10 15:08:47	1.203
+++ rxvt-unicode/src/background.C	2012/04/12 10:22:50	1.206
@@ -125,16 +125,12 @@
 static inline int
 make_align_position (int align, int window_size, int image_size)
 {
-  int diff = window_size - image_size;
-  int smaller = min (image_size, window_size);
-
   if (align >= 0 && align <= 100)
-    return diff * align / 100;
-  else if (align > 100 && align <= 200)
-    return (align - 100) * smaller / 100 + window_size - smaller;
-  else if (align >= -100 && align < 0)
-    return (align + 100) * smaller / 100 - image_size;
-  return 0;
+    return lerp (0, window_size - image_size, align);
+  else if (align > 100)
+    return lerp (window_size - image_size, window_size, align - 100);
+  else
+    return lerp (-image_size, 0, align + 100);
 }
 
 static inline int
@@ -336,12 +332,13 @@
       y = make_align_position (v_align, target_height, h);
     }
 
-  bg_flags &= ~BG_IS_SIZE_SENSITIVE;
   if (!(bg_flags & BG_TILE)
       || h_scale || v_scale
       || (!(bg_flags & BG_ROOT_ALIGN) && (h_align || v_align))
-      || w > target_width || h > target_height)
+      || image_width > target_width || image_height > target_height)
     bg_flags |= BG_IS_SIZE_SENSITIVE;
+  else
+    bg_flags &= ~BG_IS_SIZE_SENSITIVE;
 }
 
 #  ifdef HAVE_PIXBUF
@@ -677,10 +674,10 @@
       v_blurRadius = vr;
     }
 
-  if (h_blurRadius == 0 || v_blurRadius == 0)
-    bg_flags &= ~BG_NEEDS_BLUR;
-  else
+  if (h_blurRadius && v_blurRadius)
     bg_flags |= BG_NEEDS_BLUR;
+  else
+    bg_flags &= ~BG_NEEDS_BLUR;
 
   return changed;
 }