xterm: fix for filcker problem with animated SIXEL graphics (http://youtu.be/_kUzRHVllJg)

xterm-prevent-sixel-filcker.diff

--- xterm-310/graphics.c	2014-07-13 10:19:45.000000000 +0900
+++ xterm-310/graphics.c	2014-08-15 01:20:53.000000000 +0900
@@ -847,6 +847,7 @@
     XGCValues xgcv;
     XtGCMask mask;
     int holes, total;
+    Pixmap pixmap;
 
     TRACE(("refreshing graphic from %d,%d %dx%d (valid=%d, size=%dx%d, scale=%dx%d max=%dx%d) at base=%d,%d\n",
 	   x, y, w, h,
@@ -864,6 +865,10 @@
     xgcv.graphics_exposures = False;
     mask = GCForeground | GCGraphicsExposures;
     graphics_gc = XCreateGC(display, vwindow, mask, &xgcv);
+    pixmap = XCreatePixmap(display, vwindow,
+			   graphic->actual_width,
+			   graphic->actual_height,
+			   XDefaultDepth(display, DefaultScreen(display)));
 
     pw = graphic->pixw;
     ph = graphic->pixh;
@@ -913,14 +918,20 @@
 		old_fg = color;
 	    }
 
-	    XFillRectangle(display, vwindow, graphics_gc,
-			   xbase + ctest,
-			   ybase + rtest,
+	    XFillRectangle(display, pixmap, graphics_gc,
+			   ctest,
+			   rtest,
 			   (unsigned) pw,
 			   (unsigned) ph);
 	}
     }
 
+    XCopyArea(display, pixmap, vwindow, graphics_gc,
+	      0, 0,
+	      graphic->actual_width, graphic->actual_height,
+	      xbase, ybase);
+    XFreePixmap(display, pixmap);
+
 #ifdef DEBUG_REFRESH
     {
 	XColor def;