Added support for PNGs with alpha. image_fill_background optimised.

c/Images

@@ -2199,6 +2199,10 @@ static _kernel_oserror * image_update_image(browser_data * b, int image, BBox *
       animhandler = 1;
     }
 
+  }
+
+  if (idata[image].istore -> RegisterFiller)
+  {
     #ifdef STRICT_PARSER
 
       {
@@ -2899,16 +2903,16 @@ _kernel_oserror * image_fill_background(void * handle, int * i)
 
     if (w < 1 || h < 1) return NULL;
 
-    redraw.xmin = xorigin;
-    redraw.ymin = -idata[ximage].istore->height_os;
+    redraw.xmin = -((-xorigin) % w);
+    redraw.ymin = -h /*-idata[ximage].istore->height_os */;
     redraw.xmax = idata[ximage].istore->width_os;
-    redraw.ymax = yorigin;
+    redraw.ymax = idata[ximage].istore->height_os + (yorigin - idata[ximage].istore->height_os) % h - 1;
 
-    /* Render the image over the redraw region, with an unscaled plot */
+    /* Render the image over the redraw region, with a scaled plot */
 
-    for (y = redraw.ymax; y >= redraw.ymin - h; y -= h)
+    for (y = redraw.ymax; y >= redraw.ymin; y -= h)
     {
-      for (x = redraw.xmin; x <= redraw.xmax + w; x += w)
+      for (x = redraw.xmin; x <= redraw.xmax; x += w)
       {
         e = (idata[bimage].istore -> Render(idata[bimage].istore,
                                            x,
@@ -2943,16 +2947,16 @@ _kernel_oserror * image_fill_background(void * handle, int * i)
 
     if (w < 1 || h < 1) return NULL;
 
-    redraw.xmin = xorigin;
-    redraw.ymin = -idata[ximage].istore->height_os;
+    redraw.xmin = -((-xorigin) % w);
+    redraw.ymin = -h /*-idata[ximage].istore->height_os */;
     redraw.xmax = idata[ximage].istore->width_os;
-    redraw.ymax = yorigin;
+    redraw.ymax = idata[ximage].istore->height_os + (yorigin - idata[ximage].istore->height_os) % h - 1;
 
     /* Render the image over the redraw region, with an unscaled plot */
 
-    for (y = redraw.ymax; y >= redraw.ymin - h; y -= h)
+    for (y = redraw.ymax; y >= redraw.ymin; y -= h)
     {
-      for (x = redraw.xmin; x <= redraw.xmax + w; x += w)
+      for (x = redraw.xmin; x <= redraw.xmax; x += w)
       {
         e = (idata[bimage].istore -> Render(idata[bimage].istore,
                                            x,