Add border-native option to --tmux flag (#4157)

This commit adds the `border-native` resulting in the following:

```
--tmux[=[center|top|bottom|left|right][,SIZE[%]][,SIZE[%]][,border-native]]
```

By default, when not specified, the `-B` flag is passed to the
`tmux popup-window` command such that no border is drawn around
the tmux popup window.

When the `border-native` option is present, the `-B` flag is omitted
and the popup window is drawn using the border style configured in
the tmux config file.

Fixes #4156

Signed-off-by: Andreas Auernhammer <github@aead.dev>
Co-authored-by: Junegunn Choi <junegunn.c@gmail.com>

src/tmux.go

@@ -9,13 +9,16 @@ import (
 
 func runTmux(args []string, opts *Options) (int, error) {
 	// Prepare arguments
-	fzf := args[0]
-	args = append([]string{"--bind=ctrl-z:ignore"}, args[1:]...)
-	if opts.BorderShape == tui.BorderUndefined {
+	fzf, rest := args[0], args[1:]
+	args = []string{"--bind=ctrl-z:ignore"}
+	if !opts.Tmux.border && opts.BorderShape == tui.BorderUndefined {
 		args = append(args, "--border")
 	}
+	if opts.Tmux.border && opts.Margin == defaultMargin() {
+		args = append(args, "--margin=0,1")
+	}
 	argStr := escapeSingleQuote(fzf)
-	for _, arg := range args {
+	for _, arg := range append(args, rest...) {
 		argStr += " " + escapeSingleQuote(arg)
 	}
 	argStr += ` --no-tmux --no-height`
@@ -33,7 +36,10 @@ func runTmux(args []string, opts *Options) (int, error) {
 	// M        Both    The mouse position
 	// W        Both    The window position on the status line
 	// S        -y      The line above or below the status line
-	tmuxArgs := []string{"display-popup", "-E", "-B", "-d", dir}
+	tmuxArgs := []string{"display-popup", "-E", "-d", dir}
+	if !opts.Tmux.border {
+		tmuxArgs = append(tmuxArgs, "-B")
+	}
 	switch opts.Tmux.position {
 	case posUp:
 		tmuxArgs = append(tmuxArgs, "-xC", "-y0")