Fix preview scrollbar not rendered after toggle-preview

Fix #4732

src/terminal.go

@@ -4630,7 +4630,7 @@ func (t *Terminal) renderPreviewScrollbar(yoff int, barLength int, barStart int)
 	w := t.pborder.Width()
 	xw := [2]int{t.pwindow.Left(), t.pwindow.Width()}
 	redraw := false
-	if len(t.previewer.bar) != height || t.previewer.xw != xw {
+	if len(t.previewer.bar) != height || t.previewer.xw != xw || t.previewed.version != t.previewer.version {
 		redraw = true
 		t.previewer.bar = make([]bool, height)
 		t.previewer.xw = xw

test/test_preview.rb

@@ -623,4 +623,20 @@ class TestPreview < TestInteractive
       assert_equal(0, lines.count { |line| line.include?('│ h') })
     end
   end
+
+  def test_preview_toggle_should_redraw_scrollbar
+    tmux.send_keys %(seq 1 | #{FZF} --no-border --scrollbar --preview 'seq $((FZF_PREVIEW_LINES + 1))' --preview-border line --bind tab:toggle-preview --header foo --header-border --footer bar --footer-border), :Enter
+    tmux.until do |lines|
+      assert_equal 1, lines.match_count
+      assert_operator lines.count { |line| line.end_with?('│') }, :>, 2
+    end
+    tmux.send_keys :Tab
+    tmux.until do |lines|
+      assert_equal(2, lines.count { |line| line.end_with?('│') })
+    end
+    tmux.send_keys :Tab
+    tmux.until do |lines|
+      assert_operator lines.count { |line| line.end_with?('│') }, :>, 2
+    end
+  end
 end