Improve handling of iconification of child frames (Bug#28611)

* src/frame.c (Ficonify_frame): Handle `iconify-child-frame' option.
(syms_of_frame): New symbols Qiconify_top_level and Qmake_invisible.
(iconify_child_frame): New option.
* lisp/cus-start.el (iconify-child-frame): Add customization
properties.
* doc/lispref/frames.texi (Child Frames): Describe new option
`iconify-child-frame'.  Don't index "top-level frame" twice.

1 files changed, 7 insertions, 0 deletions

diff --git a/lisp/cus-start.el b/lisp/cus-start.el
index b197f2f1de5..fd015b70ca3 100644
--- a/lisp/cus-start.el
+++ b/lisp/cus-start.el
@@ -319,6 +319,13 @@ Leaving \"Default\" unchecked is equivalent with specifying a default of
                                             (const :tag "Always" t)
                                             (repeat (symbol :tag "Parameter")))
                                            "25.1")
+             (iconify-child-frame frames
+                                  (choice
+                                   (const :tag "Do nothing" nil)
+                                   (const :tag "Iconify top level frame instead" iconify-top-level)
+                                   (const :tag "Make frame invisible instead" make-invisible)
+                                   (const :tag "Iconify" t))
+                                  "26.1")
              (tooltip-reuse-hidden-frame tooltip boolean "26.1")
              ;; fringe.c
              (overflow-newline-into-fringe fringe boolean)