Default to native border for Zellij floating pane (#4854)

The native border is the handle for moving and resizing the pane with
the mouse, so use it by default, consistent with tmux. fzf draws its
own border only when a border style is explicitly specified with
--border. Extract the shared native-border decision into a helper.

src/tmux.go

@@ -183,17 +183,24 @@ exit "$code"`, newPane, code, signal, signal, code, code, code)
 	}, opts, true)
 }
 
+// Whether to use the multiplexer's native border for the floating pane. Its
+// native border is the handle that makes the pane movable and resizable with
+// the mouse, so it is the default; 'border-native' forces it. It is not used
+// when a border style is explicitly specified with --border, so that the
+// fzf-drawn border is the only one shown. 'none' and 'line' are treated as no
+// border; fzf draws no box for either, and 'line' only makes sense with
+// --height.
+func nativeBorder(opts *Options) bool {
+	return opts.Tmux.border || opts.BorderShape == tui.BorderUndefined ||
+		opts.BorderShape == tui.BorderLine || opts.BorderShape == tui.BorderNone
+}
+
 func runTmux(args []string, opts *Options) (int, error) {
 	// On tmux 3.7 or above, fzf runs in a floating pane instead of a popup.
-	// A floating pane always has a native border, so 'border-native' is
-	// implied. When a border style is explicitly specified with --border, a
+	// When the native border is not used (an explicit --border style), a
 	// popup is used instead so that the fzf-drawn border is the only border
-	// shown; the native border of a floating pane cannot be removed. 'none'
-	// and 'line' are treated as no border; fzf draws no box for either, and
-	// 'line' only makes sense with --height. Give 'border-native' to force
-	// a floating pane nonetheless.
-	if opts.Tmux.border || opts.BorderShape == tui.BorderUndefined ||
-		opts.BorderShape == tui.BorderLine || opts.BorderShape == tui.BorderNone {
+	// shown; the native border of a tmux floating pane cannot be removed.
+	if nativeBorder(opts) {
 		if windowWidth, windowHeight, ok := tmuxFloatingPaneInfo(); ok {
 			opts.Tmux.border = true
 			argStr, dir := popupArgStr(args, opts)

src/zellij.go

@@ -2,9 +2,18 @@ package fzf
 
 import (
 	"os/exec"
+
+	"github.com/junegunn/fzf/src/tui"
 )
 
 func runZellij(args []string, opts *Options) (int, error) {
+	// Use the native Zellij border by default, consistent with tmux, so that
+	// the pane can be moved and resized with the mouse. Set before
+	// popupArgStr so that it does not inject an fzf border. fzf draws its own
+	// border instead when a border style is explicitly specified.
+	if nativeBorder(opts) {
+		opts.Tmux.border = true
+	}
 	argStr, dir := popupArgStr(args, opts)
 
 	zellijArgs := []string{
@@ -13,6 +22,22 @@ func runZellij(args []string, opts *Options) (int, error) {
 	}
 	if !opts.Tmux.border {
 		zellijArgs = append(zellijArgs, "--borderless", "true")
+	} else {
+		// Set --border-label as the name of the pane, displayed on the
+		// native border. The label is left to fzf when it draws its own
+		// border with the label on it (border-native with an explicit
+		// --border style). Empty otherwise, to override the default name
+		// (the running command). Passed as a single argument in the
+		// --name=label form; the detached form fails to parse when the
+		// label starts with a hyphen. No escaping is needed beyond
+		// stripping ANSI sequences fzf would otherwise render itself.
+		// --border-label-pos is ignored.
+		label := ""
+		if opts.BorderShape == tui.BorderUndefined || opts.BorderShape == tui.BorderLine ||
+			opts.BorderShape == tui.BorderNone {
+			label, _, _ = extractColor(opts.BorderLabel.label, nil, nil)
+		}
+		zellijArgs = append(zellijArgs, "--name="+label)
 	}
 	switch opts.Tmux.position {
 	case posUp: