Warp patch

Warps the mouse cursor to the center of the currently focused
window or screen when the mouse cursor is
  (a) on a different screen, or
  (b) on top of a different window.

This version properly handles warping to windows that have not been
mapped yet (before it resulted in a change of the stack order).
See the discussion in (thanks goes to Bakkeby):
    https://github.com/bakkeby/patches/issues/60

dwm.c

@@ -246,6 +246,7 @@ static void updatetitle(Client *c);
 static void updatewindowtype(Client *c);
 static void updatewmhints(Client *c);
 static void view(const Arg *arg);
+static void warp(const Client *c);
 static Client *wintoclient(Window w);
 static Monitor *wintomon(Window w);
 static int xerror(Display *dpy, XErrorEvent *ee);
@@ -909,6 +910,7 @@ focusmon(const Arg *arg)
 	unfocus(selmon->sel, 0);
 	selmon = m;
 	focus(NULL);
+	warp(selmon->sel);
 }
 
 void
@@ -1542,6 +1544,8 @@ restack(Monitor *m)
 				wc.sibling = c->win;
 			}
 	}
+	if (m == selmon && (m->tagset[m->seltags] & m->sel->tags) && m->lt[m->sellt]->arrange != &monocle)
+		warp(m->sel);
 	XSync(dpy, False);
 	while (XCheckMaskEvent(dpy, EnterWindowMask, &ev));
 }
@@ -2374,6 +2378,28 @@ view(const Arg *arg)
 	arrange(selmon);
 }
 
+void
+warp(const Client *c)
+{
+	int x, y;
+
+	if (!c) {
+		XWarpPointer(dpy, None, root, 0, 0, 0, 0, selmon->wx + selmon->ww / 2, selmon->wy + selmon->wh / 2);
+		return;
+	}
+
+	if (!getrootptr(&x, &y) ||
+		(x > c->x - c->bw &&
+		 y > c->y - c->bw &&
+		 x < c->x + c->w + c->bw*2 &&
+		 y < c->y + c->h + c->bw*2) ||
+		(y > c->mon->by && y < c->mon->by + bh) ||
+		(c->mon->topbar && !y))
+		return;
+
+	XWarpPointer(dpy, None, c->win, 0, 0, 0, 0, c->w / 2, c->h / 2);
+}
+
 Client *
 wintoclient(Window w)
 {