Add toggle-track action

CHANGELOG.md

@@ -3,6 +3,17 @@ CHANGELOG
 
 0.39.1
 ------
+- Added `toggle-track` action. Temporarily enabling tracking is useful when
+  you want to see the surrounding items by deleting the query string.
+  ```sh
+  export FZF_CTRL_R_OPTS="
+    --preview 'echo {}' --preview-window up:3:hidden:wrap
+    --bind 'ctrl-/:toggle-preview'
+    --bind 'ctrl-t:toggle-track'
+    --bind 'ctrl-y:execute-silent(echo -n {2..} | pbcopy)+abort'
+    --color header:italic
+    --header 'Press CTRL-Y to copy command into clipboard'"
+  ```
 - Fixed `--track` behavior when used with `--tac`
     - However, using `--track` with `--tac` is not recommended. The resulting
       behavior can be very confusing.

src/terminal.go

@@ -337,6 +337,7 @@ const (
 	actToggleUp
 	actToggleIn
 	actToggleOut
+	actToggleTrack
 	actDown
 	actUp
 	actPageUp
@@ -1464,6 +1465,9 @@ func (t *Terminal) printInfo() {
 			output += " -S"
 		}
 	}
+	if t.track {
+		output += " +T"
+	}
 	if t.multi > 0 {
 		if t.multi == maxMulti {
 			output += fmt.Sprintf(" (%d)", len(t.selected))
@@ -3274,6 +3278,9 @@ func (t *Terminal) Loop() {
 				t.paused = !t.paused
 				changed = !t.paused
 				req(reqPrompt)
+			case actToggleTrack:
+				t.track = !t.track
+				req(reqInfo)
 			case actEnableSearch:
 				t.paused = false
 				changed = true

test/test_go.rb

@@ -2681,7 +2681,7 @@ class TestGoFZF < TestBase
   end
 
   def test_track
-    tmux.send_keys "seq 1000 | #{FZF} --query 555 --track", :Enter
+    tmux.send_keys "seq 1000 | #{FZF} --query 555 --track --bind t:toggle-track", :Enter
     tmux.until do |lines|
       assert_equal 1, lines.match_count
       assert_includes lines, '> 555'
@@ -2701,6 +2701,35 @@ class TestGoFZF < TestBase
       assert_equal 1000, lines.match_count
       assert_equal '> 555', lines[index]
     end
+    tmux.send_keys '555'
+    tmux.until do |lines|
+      assert_equal 1, lines.match_count
+      assert_includes lines, '> 555'
+      assert_includes lines[-2], '+T'
+    end
+    tmux.send_keys 't'
+    tmux.until do |lines|
+      refute_includes lines[-2], '+T'
+    end
+    tmux.send_keys :BSpace
+    tmux.until do |lines|
+      assert_equal 28, lines.match_count
+      assert_includes lines, '> 55'
+    end
+    tmux.send_keys :BSpace
+    tmux.until do |lines|
+      assert_equal 271, lines.match_count
+      assert_includes lines, '> 5'
+    end
+    tmux.send_keys 't'
+    tmux.until do |lines|
+      assert_includes lines[-2], '+T'
+    end
+    tmux.send_keys :BSpace
+    tmux.until do |lines|
+      assert_equal 1000, lines.match_count
+      assert_includes lines, '> 5'
+    end
   end
 
   def test_one