Implement `follow-tooltip' on NS as well

* lisp/term/ns-win.el (x-begin-drag): Pass `follow-tooltip'.
* src/nsfns.m (Fx_show_tip): Record last dx and dy.
(syms_of_nsfns): New staticpros.
* src/nsmenu.m ([EmacsTooltip moveTo:]): New method.

* src/nsselect.m (Fns_begin_drag): New parameter
`follow-tooltip'.

* src/nsterm.h (@interface EmacsWindow):
(EmacsTooltip): Update prototypes.
* src/nsterm.m ([EmacsWindow draggedImage:movedTo:]): Move any
tooltip to the right location.
([EmacsWindow beginDrag:forPasteboard...]): New parameter
`followTooltip'.

lisp/term/ns-win.el

@@ -896,7 +896,7 @@ See the documentation of `create-fontset-from-fontset-spec' for the format.")
   (ns-get-selection selection-symbol target-type))
 
 (defun x-begin-drag (targets &optional action frame return-frame
-                             allow-current-frame _follow-tooltip)
+                             allow-current-frame follow-tooltip)
   "SKIP: real doc in xfns.c."
   (unless ns-dnd-selection-value
     (error "No local value for XdndSelection"))
@@ -921,7 +921,8 @@ See the documentation of `create-fontset-from-fontset-spec' for the format.")
                                               (expand-file-name
                                                ns-dnd-selection-value))))
                 pasteboard))))
-    (ns-begin-drag frame pasteboard action return-frame allow-current-frame)))
+    (ns-begin-drag frame pasteboard action return-frame
+                   allow-current-frame follow-tooltip)))
 
 (defun ns-handle-drag-motion (frame x y)
   "Handle mouse movement on FRAME at X and Y during drag-and-drop.

src/nsfns.m

@@ -63,6 +63,9 @@ static EmacsTooltip *ns_tooltip = nil;
 /* The frame of the currently visible tooltip, or nil if none.  */
 static Lisp_Object tip_frame;
 
+/* The X and Y deltas of the last call to `x-show-tip'.  */
+static Lisp_Object tip_dx, tip_dy;
+
 /* The window-system window corresponding to the frame of the
    currently visible tooltip.  */
 static NSWindow *tip_window;
@@ -3243,6 +3246,9 @@ DEFUN ("x-show-tip", Fx_show_tip, Sx_show_tip, 1, 6, 0,
   else
     CHECK_FIXNUM (dy);
 
+  tip_dx = dx;
+  tip_dy = dy;
+
   if (use_system_tooltips)
     {
       NSSize size;
@@ -3794,6 +3800,45 @@ all_nonzero_ascii (unsigned char *str, ptrdiff_t n)
 }
 @end
 
+void
+ns_move_tooltip_to_mouse_location (NSPoint screen_point)
+{
+  int root_x, root_y;
+  NSSize size;
+  NSWindow *window;
+  struct frame *tip_f;
+
+  if (!FIXNUMP (tip_dx) || !FIXNUMP (tip_dy))
+    return;
+
+  if (ns_tooltip)
+    size = [ns_tooltip frame].size;
+  else if (!FRAMEP (tip_frame)
+	   || !FRAME_LIVE_P (XFRAME (tip_frame)))
+    return;
+  else
+    {
+      tip_f = XFRAME (tip_frame);
+      window = [FRAME_NS_VIEW (tip_f) window];
+      size = [window frame].size;
+    }
+
+  root_x = screen_point.x;
+  root_y = screen_point.y;
+
+  /* We can directly use `compute_tip_xy' here, since it doesn't cons
+     nearly as much as it does on X.  */
+  compute_tip_xy (NULL, Qnil, tip_dx, tip_dy, (int) size.width,
+		  (int) size.height, &root_x, &root_y);
+
+  if (ns_tooltip)
+    [ns_tooltip moveTo: NSMakePoint (root_x, root_y)];
+  else
+    [window setFrame: NSMakeRect (root_x, root_y,
+				  size.width, size.height)
+	     display: YES];
+}
+
 /* ==========================================================================
 
     Lisp interface declaration
@@ -3902,6 +3947,10 @@ Default is t.  */);
   staticpro (&tip_last_string);
   tip_last_parms = Qnil;
   staticpro (&tip_last_parms);
+  tip_dx = Qnil;
+  staticpro (&tip_dx);
+  tip_dy = Qnil;
+  staticpro (&tip_dy);
 
 #if defined (NS_IMPL_COCOA) && MAC_OS_X_VERSION_MAX_ALLOWED >= 1080
   defsubr (&Ssystem_move_file_to_trash);

src/nsmenu.m

@@ -1497,6 +1497,15 @@ update_frame_tool_bar (struct frame *f)
   [timer retain];
 }
 
+- (void) moveTo: (NSPoint) screen_point
+{
+  [win setFrame: NSMakeRect (screen_point.x,
+			     screen_point.y,
+			     [self frame].size.width,
+			     [self frame].size.height)
+	display: YES];
+}
+
 - (void) hide
 {
   [win close];

src/nsselect.m

@@ -703,7 +703,7 @@ ns_dnd_action_from_operation (NSDragOperation operation)
     }
 }
 
-DEFUN ("ns-begin-drag", Fns_begin_drag, Sns_begin_drag, 3, 5, 0,
+DEFUN ("ns-begin-drag", Fns_begin_drag, Sns_begin_drag, 3, 6, 0,
        doc: /* Begin a drag-and-drop operation on FRAME.
 
 FRAME must be a window system frame.  PBOARD is an alist of (TYPE
@@ -729,9 +729,12 @@ other non-nil value means to do the same, but to wait for the mouse to
 leave FRAME first.
 
 If ALLOW-SAME-FRAME is nil, dropping on FRAME will result in the drop
-being ignored.  */)
+being ignored.
+
+FOLLOW-TOOLTIP means the same thing it does in `x-begin-drag'.  */)
   (Lisp_Object frame, Lisp_Object pboard, Lisp_Object action,
-   Lisp_Object return_frame, Lisp_Object allow_same_frame)
+   Lisp_Object return_frame, Lisp_Object allow_same_frame,
+   Lisp_Object follow_tooltip)
 {
   struct frame *f, *return_to;
   NSPasteboard *pasteboard;
@@ -761,7 +764,8 @@ being ignored.  */)
 		  forPasteboard: pasteboard
 		       withMode: mode
 		  returnFrameTo: &return_to
-		   prohibitSame: (BOOL) NILP (allow_same_frame)];
+		   prohibitSame: (BOOL) NILP (allow_same_frame)
+		  followTooltip: (BOOL) !NILP (follow_tooltip)];
 
   if (return_to)
     {

src/nsterm.h

@@ -426,6 +426,7 @@ enum ns_return_frame_mode
   struct frame *dnd_return_frame;
   enum ns_return_frame_mode dnd_mode;
   BOOL dnd_allow_same_frame;
+  BOOL dnd_move_tooltip_with_frame;
 }
 
 #ifdef NS_IMPL_GNUSTEP
@@ -446,7 +447,8 @@ enum ns_return_frame_mode
 		forPasteboard: (NSPasteboard *) pasteboard
 		     withMode: (enum ns_return_frame_mode) mode
 		returnFrameTo: (struct frame **) frame_return
-	    prohibitSame: (BOOL) prohibit_same_frame;
+		 prohibitSame: (BOOL) prohibit_same_frame
+		followTooltip: (BOOL) follow_tooltip;
 - (BOOL) mustNotDropOn: (NSView *) receiver;
 @end
 
@@ -630,19 +632,21 @@ enum ns_return_frame_mode
 #else
 @interface EmacsTooltip : NSObject
 #endif
-  {
-    NSWindow *win;
-    NSTextField *textField;
-    NSTimer *timer;
-  }
+{
+  NSWindow *win;
+  NSTextField *textField;
+  NSTimer *timer;
+}
+
 - (instancetype) init;
-- (void) setText: (char *)text;
-- (void) setBackgroundColor: (NSColor *)col;
-- (void) setForegroundColor: (NSColor *)col;
-- (void) showAtX: (int)x Y: (int)y for: (int)seconds;
+- (void) setText: (char *) text;
+- (void) setBackgroundColor: (NSColor *) col;
+- (void) setForegroundColor: (NSColor *) col;
+- (void) showAtX: (int) x Y: (int) y for: (int) seconds;
 - (void) hide;
 - (BOOL) isActive;
 - (NSRect) frame;
+- (void) moveTo: (NSPoint) screen_point;
 @end
 
 
@@ -1140,6 +1144,9 @@ extern const char *ns_get_pending_menu_title (void);
 #endif
 
 /* Implemented in nsfns, published in nsterm.  */
+#ifdef __OBJC__
+extern void ns_move_tooltip_to_mouse_location (NSPoint);
+#endif
 extern void ns_implicitly_set_name (struct frame *f, Lisp_Object arg,
                                     Lisp_Object oldval);
 extern void ns_set_scroll_bar_default_width (struct frame *f);

src/nsterm.m

@@ -9629,35 +9629,45 @@ nswindow_orderedIndex_sort (id w1, id w2, void *c)
   selected_op = operation;
 }
 
-#ifdef NS_IMPL_COCOA
 - (void) draggedImage: (NSImage *) dragged_image
 	      movedTo: (NSPoint) screen_point
 {
+  NSPoint mouse_loc;
+#ifdef NS_IMPL_COCOA
   NSInteger window_number;
   NSWindow *w;
-
-  if (dnd_mode == RETURN_FRAME_NEVER)
-    return;
-
-  window_number = [NSWindow windowNumberAtPoint: [NSEvent mouseLocation]
-		    belowWindowWithWindowNumber: 0];
-  w = [NSApp windowWithWindowNumber: window_number];
-
-  if (!w || w != self)
-    dnd_mode = RETURN_FRAME_NOW;
-
-  if (dnd_mode != RETURN_FRAME_NOW
-      || ![[w delegate] isKindOfClass: [EmacsView class]])
-    return;
-
-  dnd_return_frame = ((EmacsView *) [w delegate])->emacsframe;
-
-  /* FIXME: there must be a better way to leave the event loop.  */
-  [NSException raise: @""
-	      format: @"Must return DND frame"];
-}
 #endif
 
+  mouse_loc = [NSEvent mouseLocation];
+
+#ifdef NS_IMPL_COCOA
+  if (dnd_mode != RETURN_FRAME_NEVER)
+    {
+      window_number = [NSWindow windowNumberAtPoint: mouse_loc
+			belowWindowWithWindowNumber: 0];
+      w = [NSApp windowWithWindowNumber: window_number];
+
+      if (!w || w != self)
+	dnd_mode = RETURN_FRAME_NOW;
+
+      if (dnd_mode != RETURN_FRAME_NOW
+	  || ![[w delegate] isKindOfClass: [EmacsView class]])
+	goto out;
+
+      dnd_return_frame = ((EmacsView *) [w delegate])->emacsframe;
+
+      /* FIXME: there must be a better way to leave the event loop.  */
+      [NSException raise: @""
+		  format: @"Must return DND frame"];
+    }
+#endif
+
+ out:
+
+  if (dnd_move_tooltip_with_frame)
+    ns_move_tooltip_to_mouse_location (mouse_loc);
+}
+
 - (BOOL) mustNotDropOn: (NSView *) receiver
 {
   return ([receiver window] == self
@@ -9669,6 +9679,7 @@ nswindow_orderedIndex_sort (id w1, id w2, void *c)
 		     withMode: (enum ns_return_frame_mode) mode
 		returnFrameTo: (struct frame **) frame_return
 		 prohibitSame: (BOOL) prohibit_same_frame
+		followTooltip: (BOOL) follow_tooltip
 {
   NSImage *image;
 #ifdef NS_IMPL_COCOA
@@ -9681,6 +9692,7 @@ nswindow_orderedIndex_sort (id w1, id w2, void *c)
   dnd_mode = mode;
   dnd_return_frame = NULL;
   dnd_allow_same_frame = !prohibit_same_frame;
+  dnd_move_tooltip_with_frame = follow_tooltip;
 
   /* Now draw transparency onto the image.  */
   [image lockFocus];
@@ -9728,6 +9740,10 @@ nswindow_orderedIndex_sort (id w1, id w2, void *c)
 #endif
   unblock_input ();
 
+  /* The drop happened, so delete the tooltip.  */
+  if (follow_tooltip)
+    Fx_hide_tip ();
+
   /* Assume all buttons have been released since the drag-and-drop
      operation is now over.  */
   if (!dnd_return_frame)