Support Xinerama in wmsetbg.

Allow wmsetbg to revert to pre-0.90.0 behaviour when choosing a
background image that is large enough to span several heads in a
Xinerama setup.  If the -X flag is passed to wmsetbg, the background
image will be stretched to fill the logical screen (as it would be by
default in older versions of wmsetbg) instead of being tiled across
screens.

util/wmsetbg.c

@@ -80,6 +80,9 @@ int scrX, scrY;
 WXineramaInfo xineInfo;
 
 Bool smooth = False;
+#ifdef XINERAMA
+Bool xineStretch = False;
+#endif
 
 Pixmap CurrentPixmap = None;
 char *PixmapPath = NULL;
@@ -543,7 +546,7 @@ BackgroundTexture *parseTexture(RContext * rc, char *text)
 				texture->height = scrHeight;
 
 #ifdef XINERAMA
-				if (xineInfo.count) {
+				if (xineInfo.count && ! xineStretch) {
 					int i;
 					for (i = 0; i < xineInfo.count; ++i) {
 						applyImage(rc, texture, image, type[0],
@@ -1214,6 +1217,9 @@ void print_help(char *ProgName)
 	P(" -d, --dither	 		dither image");
 	P(" -m, --match			match  colors");
 	P(" -S, --smooth			smooth scaled image");
+#ifdef XINERAMA
+	P(" -X, --xinerama			stretch image across Xinerama heads");
+#endif
 	P(" -b, --back-color <color>	background color");
 	P(" -t, --tile			tile   image");
 	P(" -e, --center			center image");
@@ -1319,6 +1325,10 @@ int main(int argc, char **argv)
 			obey_user++;
 		} else if (strcmp(argv[i], "-S") == 0 || strcmp(argv[i], "--smooth") == 0) {
 			smooth = True;
+#ifdef XINERAMA
+		} else if (strcmp(argv[i], "-X") == 0 || strcmp(argv[i], "--xinerama") == 0) {
+			xineStretch = True;
+#endif
 		} else if (strcmp(argv[i], "-u") == 0 || strcmp(argv[i], "--update-wmaker") == 0) {
 			update++;
 		} else if (strcmp(argv[i], "-D") == 0 || strcmp(argv[i], "--update-domain") == 0) {