Fix tool-tip display when display margins are non-zero by default

* src/buffer.h (bset_left_margin_cols, bset_right_margin_cols):
New inline functions.
* src/xfns.c (Fx_show_tip):
* src/w32fns.c (Fx_show_tip): Force display margins of the tip
buffer to zero, as it will be displayed in a pseudo-window, which
doesn't support display margins.  (Bug#29627)

4 files changed, 26 insertions, 3 deletions

diff --git a/src/buffer.h b/src/buffer.h
index 46c7c6e5ad6..ecd2360dbca 100644
--- a/src/buffer.h
+++ b/src/buffer.h
@@ -949,6 +949,16 @@ bset_display_count (struct buffer *b, Lisp_Object val)
   b->display_count_ = val;
 }
 INLINE void
+bset_left_margin_cols (struct buffer *b, Lisp_Object val)
+{
+  b->left_margin_cols_ = val;
+}
+INLINE void
+bset_right_margin_cols (struct buffer *b, Lisp_Object val)
+{
+  b->right_margin_cols_ = val;
+}
+INLINE void
 bset_display_time (struct buffer *b, Lisp_Object val)
 {
   b->display_time_ = val;
diff --git a/src/w32fns.c b/src/w32fns.c
index 43af1122fad..b81cd70e0a7 100644
--- a/src/w32fns.c
+++ b/src/w32fns.c
@@ -7346,6 +7346,7 @@ Text larger than the specified size is clipped.  */)
   ptrdiff_t count = SPECPDL_INDEX ();
   ptrdiff_t count_1;
   Lisp_Object window, size;
+  Lisp_Object tip_buf;
   AUTO_STRING (tip, " *tip*");
 
   specbind (Qinhibit_redisplay, Qt);
@@ -7503,7 +7504,12 @@ Text larger than the specified size is clipped.  */)
 
   tip_f = XFRAME (tip_frame);
   window = FRAME_ROOT_WINDOW (tip_f);
-  set_window_buffer (window, Fget_buffer_create (tip), false, false);
+  tip_buf = Fget_buffer_create (tip);
+  /* We will mark the tip window a "pseudo-window" below, and such
+     windows cannot have display margins.  */
+  bset_left_margin_cols (XBUFFER (tip_buf), make_number (0));
+  bset_right_margin_cols (XBUFFER (tip_buf), make_number (0));
+  set_window_buffer (window, tip_buf, false, false);
   w = XWINDOW (window);
   w->pseudo_window_p = true;
 
diff --git a/src/window.h b/src/window.h
index 25c9686a9f0..563a6f6ff0d 100644
--- a/src/window.h
+++ b/src/window.h
@@ -370,7 +370,8 @@ struct window
     bool_bf must_be_updated_p : 1;
 
     /* Flag indicating that this window is not a real one.
-       Currently only used for menu bar windows of frames.  */
+       Currently only used for menu bar windows, for tool bar windows,
+       and for tooltips.  */
     bool_bf pseudo_window_p : 1;
 
     /* True means fringes are drawn outside display margins.
diff --git a/src/xfns.c b/src/xfns.c
index bbe73aa7c28..044f14876e3 100644
--- a/src/xfns.c
+++ b/src/xfns.c
@@ -6623,6 +6623,7 @@ Text larger than the specified size is clipped.  */)
   ptrdiff_t count = SPECPDL_INDEX ();
   ptrdiff_t count_1;
   Lisp_Object window, size;
+  Lisp_Object tip_buf;
   AUTO_STRING (tip, " *tip*");
 
   specbind (Qinhibit_redisplay, Qt);
@@ -6787,7 +6788,12 @@ Text larger than the specified size is clipped.  */)
 
   tip_f = XFRAME (tip_frame);
   window = FRAME_ROOT_WINDOW (tip_f);
-  set_window_buffer (window, Fget_buffer_create (tip), false, false);
+  tip_buf = Fget_buffer_create (tip);
+  /* We will mark the tip window a "pseudo-window" below, and such
+     windows cannot have display margins.  */
+  bset_left_margin_cols (XBUFFER (tip_buf), make_number (0));
+  bset_right_margin_cols (XBUFFER (tip_buf), make_number (0));
+  set_window_buffer (window, tip_buf, false, false);
   w = XWINDOW (window);
   w->pseudo_window_p = true;