runtime(dist/vim9): fix regressions in dist#vim9#Open

fixes: #16533
fixes: #16532
closes: #16535

Signed-off-by: Luca Saccarola <github.e41mv@aleeas.com>
Signed-off-by: Christian Brabandt <cb@256bit.org>

runtime/doc/eval.txt

@@ -1,4 +1,4 @@
-*eval.txt*	For Vim version 9.1.  Last change: 2025 Jan 25
+*eval.txt*	For Vim version 9.1.  Last change: 2025 Jan 29
 
 
 		  VIM REFERENCE MANUAL	  by Bram Moolenaar
@@ -4908,13 +4908,25 @@ executable.  It takes the following arguments:
 	executable	string
 
 						      *dist#vim9#Open()* *:Open*
-						      *g:Openprg*
+						      *g:Openprg* *gx*
 dist#vim9#Open(file: string) ~
 
 Opens `path` with the system default handler (macOS `open`, Windows
 `explorer.exe`, Linux `xdg-open`, …). If the variable |g:Openprg| exists the
 string specified in the variable is used instead.
 
+This function is by default called using the gx mapping.  In visual mode
+tries to open the visually selected text.
+
+Associated setting variables:
+`g:gx_word`: control how gx picks up the text under the cursor. Uses
+	     `g:netrw_gx` as a fallback for backward compatibility.
+	     (default: `<cfile>`)
+
+`g:nogx`: disables the gx mapping. Uses `g:netrw_nogx` as a fallback for
+	  backward compatibility. (default: `unset`)
+
+
 NOTE: Escaping of the path is automatically applied.
 
 Usage: >vim

runtime/doc/tags

@@ -8053,6 +8053,7 @@ gvimrc	gui.txt	/*gvimrc*
 gw	change.txt	/*gw*
 gwgw	change.txt	/*gwgw*
 gww	change.txt	/*gww*
+gx	eval.txt	/*gx*
 gzip	pi_gzip.txt	/*gzip*
 gzip-autocmd	pi_gzip.txt	/*gzip-autocmd*
 gzip-example	autocmd.txt	/*gzip-example*