emacs-28 91d71b3: Fix inset rectangle corners when sides aren't drawn (bug#51251)

[Alan Third]

branch: emacs-28
commit 91d71b38a333c9b3dc411547c1ad61f0ee63d4e6
Author: Alan Third <alan@idiocy.org>
Commit: Alan Third <alan@idiocy.org>

    Fix inset rectangle corners when sides aren't drawn (bug#51251)
    
    * src/nsterm.m (ns_draw_relief): Make the inner rectangle line up with
    the outer rectangle's edges where the edges aren't drawn.
---
 src/nsterm.m | 7 ++++++-
 1 file changed, 6 insertions(+), 1 deletion(-)

diff --git a/src/nsterm.m b/src/nsterm.m
index c6f80f8..aa29c13 100644
--- a/src/nsterm.m
+++ b/src/nsterm.m
@@ -3512,7 +3512,12 @@ ns_draw_relief (NSRect outer, int hthickness, int 
vthickness, char raised_p,
     }
 
   /* Calculate the inner rectangle.  */
-  inner = NSInsetRect (outer, hthickness, vthickness);
+  inner = NSMakeRect (NSMinX (outer) + (left_p ? hthickness : 0),
+                      NSMinY (outer) + (top_p ? vthickness : 0),
+                      NSWidth (outer) - (left_p ? hthickness : 0)
+                                      - (right_p ? hthickness : 0),
+                      NSHeight (outer) - (top_p ? vthickness : 0)
+                                       - (bottom_p ? vthickness : 0));
 
   [(raised_p ? lightCol : darkCol) set];