master 2d4b2e296b: Remove macOS drop-shadows on some frames (bug#28512)

[Alan Third]

branch: master
commit 2d4b2e296b5c13a8b8481e7c0d0c26f52d2de257
Author: Alan Third <alan@idiocy.org>
Commit: Alan Third <alan@idiocy.org>

    Remove macOS drop-shadows on some frames (bug#28512)
    
    * src/nsterm.m ([EmacsWindow setParentChildRelationships]): Remove
    shadows on undecorated child frames.
---
 src/nsterm.m | 9 +++++++++
 1 file changed, 9 insertions(+)

diff --git a/src/nsterm.m b/src/nsterm.m
index 2318f7beab..41c311e04d 100644
--- a/src/nsterm.m
+++ b/src/nsterm.m
@@ -8435,6 +8435,15 @@ not_in_argv (NSString *arg)
 #if MAC_OS_X_VERSION_MAX_ALLOWED >= 1070
   [ourView updateCollectionBehavior];
 #endif
+
+  /* Child frames are often used in ways that may mean they should
+     "disappear" into the contents of the parent frame.  macOs's
+     drop-shadows break this effect, so remove them on undecorated
+     child frames.  */
+  if (parentFrame && FRAME_UNDECORATED (ourFrame))
+    [self setHasShadow:NO];
+  else
+    [self setHasShadow:YES];
 #endif