update tag preview on arrange(). this means tag previews get

updated every time a tag gets spawned or killed, among other things.

while it is a minor slowdown, you may want to revert this commit, we'll
see how usable it is in the long run and if it creates any additional
problems

speedwm.c

@@ -1172,6 +1172,10 @@ arrange(Monitor *m)
 		restack(m);
 	} else for (m = mons; m; m = m->next)
 		arrangemon(m);
+
+#if USETAGPREVIEW
+    takepreview();
+#endif
 }
 
 void
@@ -5970,6 +5974,7 @@ spawn(const Arg *arg)
 
 		setsid();
 		execvp(((char **)arg->v)[0], (char **)arg->v);
+
 		die("speedwm: execvp '%s' failed:", ((char **)arg->v)[0]);
 	}
 }
@@ -6986,6 +6991,9 @@ view(const Arg *arg)
 	focus(NULL);
 	arrange(NULL);
 	updatecurrentdesktop();
+#if USETAGPREVIEW
+    takepreview();
+#endif
 }
 
 #if USEMOUSE