Fix `change-preview` reset by `change-preview-window`

Fix #3770

src/terminal.go

@@ -4088,6 +4088,7 @@ func (t *Terminal) Loop() {
 
 				// Reset preview options and apply the additional options
 				t.previewOpts = t.initialPreviewOpts
+				t.previewOpts.command = currentPreviewOpts.command
 
 				// Split window options
 				tokens := strings.Split(a.a, "|")

test/test_go.rb

@@ -2693,6 +2693,13 @@ class TestGoFZF < TestBase
     end
   end
 
+  def test_change_preview_window_should_not_reset_change_preview
+    tmux.send_keys "#{FZF} --preview-window up,border-none --bind 'start:change-preview(echo hello)' --bind 'enter:change-preview-window(border-left)'", :Enter
+    tmux.until { |lines| assert_equal 'hello', lines[0] }
+    tmux.send_keys :Enter
+    tmux.until { |lines| assert_equal '│ hello', lines[0] }
+  end
+
   def test_change_preview_window_rotate
     tmux.send_keys "seq 100 | #{FZF} --preview-window left,border-none --preview 'echo hello' --bind '" \
       "a:change-preview-window(right|down|up|hidden|)'", :Enter