diff --git a/notebooks/notebook-ui/src/org/jetbrains/plugins/notebooks/ui/visualization/NotebookAboveCellDelimiterPanel.kt b/notebooks/notebook-ui/src/org/jetbrains/plugins/notebooks/ui/visualization/NotebookAboveCellDelimiterPanel.kt
index 4156534cab53..4343c17a2f76 100644
--- a/notebooks/notebook-ui/src/org/jetbrains/plugins/notebooks/ui/visualization/NotebookAboveCellDelimiterPanel.kt
+++ b/notebooks/notebook-ui/src/org/jetbrains/plugins/notebooks/ui/visualization/NotebookAboveCellDelimiterPanel.kt
@@ -4,14 +4,18 @@ import com.intellij.openapi.actionSystem.AnAction
 import com.intellij.openapi.editor.Editor
 import com.intellij.openapi.editor.ex.EditorEx
 import com.intellij.openapi.project.ProjectManager
+import com.intellij.uiDesigner.UIFormXmlConstants
 import java.awt.*
 import javax.swing.JComponent
 import javax.swing.JLayeredPane
 import javax.swing.JPanel
 
+internal typealias BackgroundColorToCellRoofColor = Pair<Color, Color?>
+
 class NotebookAboveCellDelimiterPanel(val editor: Editor) : JPanel(GridBagLayout()) {
-  internal inner class ColoursChangeListenerAdapter(var isCodeCell: Boolean = false) {
-    private lateinit var currentColorsPalette: Pair<Color, Color?>
+
+  internal inner class ColorsChangeListenerAdapter {
+    private lateinit var currentColorsPalette: BackgroundColorToCellRoofColor
 
     private fun recreatePalette() {
       val newBackgroundColor = editor.colorsScheme.defaultBackground
@@ -35,7 +39,7 @@ class NotebookAboveCellDelimiterPanel(val editor: Editor) : JPanel(GridBagLayout
       delimiterPanel: JPanel,
       codeRoofPanel: JPanel,
       cellBordersPanels: Iterable<JPanel>,
-      ) {
+    ) {
       if (::currentColorsPalette.isInitialized && backgroundColor == currentColorsPalette.first) return
 
       recreatePalette()
@@ -46,14 +50,13 @@ class NotebookAboveCellDelimiterPanel(val editor: Editor) : JPanel(GridBagLayout
     }
   }
 
-  private val colorsChangeListenerAdapter = ColoursChangeListenerAdapter()
+  private val colorsChangeListenerAdapter = ColorsChangeListenerAdapter()
   val actions = ArrayList<AnAction>()
   var isCodeCell = false
 
   fun initialize(actions: Array<AnAction>, isCodeCell: Boolean) {
     this.actions.addAll(actions)
     this.isCodeCell = isCodeCell
-    colorsChangeListenerAdapter.isCodeCell = isCodeCell
 
     val backgroundColor = editor.colorsScheme.defaultBackground
     val cellRoofColor = if (isCodeCell) editor.notebookAppearance.getCodeCellBackground(editor.colorsScheme) else backgroundColor
@@ -108,11 +111,12 @@ class NotebookAboveCellDelimiterPanel(val editor: Editor) : JPanel(GridBagLayout
       }
     }
 
-    addPropertyChangeListener("border") {
+    addPropertyChangeListener(UIFormXmlConstants.ELEMENT_FONT) {
       val newBackgroundColor = editor.colorsScheme.defaultBackground
       colorsChangeListenerAdapter.propertyChanged(
         newBackgroundColor,
-        delimiterPanel, codeRoofPanel, listOf(leftPanel, rightPanel))
+        delimiterPanel, codeRoofPanel, listOf(leftPanel, rightPanel)
+      )
     }
   }
 
diff --git a/notebooks/notebook-ui/src/org/jetbrains/plugins/notebooks/ui/visualization/NotebookBelowCellDelimiterPanel.kt b/notebooks/notebook-ui/src/org/jetbrains/plugins/notebooks/ui/visualization/NotebookBelowCellDelimiterPanel.kt
index 043763b5cb8f..1aee803a3f57 100644
--- a/notebooks/notebook-ui/src/org/jetbrains/plugins/notebooks/ui/visualization/NotebookBelowCellDelimiterPanel.kt
+++ b/notebooks/notebook-ui/src/org/jetbrains/plugins/notebooks/ui/visualization/NotebookBelowCellDelimiterPanel.kt
@@ -15,9 +15,8 @@ import javax.swing.JPanel
 import javax.swing.JProgressBar
 import kotlin.math.max
 
-class NotebookBelowCellDelimiterPanel : JPanel(GridLayout(1, 1)) {
+class NotebookBelowCellDelimiterPanel(val editor: EditorImpl) : JPanel(GridLayout(1, 1)) {
   private val steadyUI = JupyterProgressBarUI()
-  private lateinit var editor: EditorImpl
   private var shouldUseCustomBackground = false
   private val progress = object : JProgressBar(0, 100) {
     init {
@@ -31,12 +30,11 @@ class NotebookBelowCellDelimiterPanel : JPanel(GridLayout(1, 1)) {
     }
   }
 
-  fun initialize(editor: EditorImpl, @Nls executionTimeDetails: String?, hasProgressBar: Boolean) {
+  fun initialize(@Nls executionTimeDetails: String?, hasProgressBar: Boolean) {
     val notebookAppearance = editor.notebookAppearance
     val customHeight = if (executionTimeDetails != null) notebookAppearance.EXECUTION_TIME_HEIGHT else notebookAppearance.SPACER_HEIGHT
     preferredSize = Dimension(preferredSize.width, customHeight)
     background = editor.colorsScheme.defaultBackground
-    this.editor = editor
 
     if (executionTimeDetails != null) {
       val label = JLabel(executionTimeDetails)
@@ -59,10 +57,12 @@ class NotebookBelowCellDelimiterPanel : JPanel(GridLayout(1, 1)) {
   }
 
   override fun updateUI() {
-    if (::editor.isInitialized) {
-      background = if (shouldUseCustomBackground)
-        editor.notebookAppearance.getCodeCellBackground(editor.colorsScheme)
-      else editor.colorsScheme.defaultBackground
+    // This method is called within constructor of JPanel, at this time state is not yet initialised, reference is null.
+    if (editor != null) {
+      background =
+        if (shouldUseCustomBackground)
+          editor.notebookAppearance.getCodeCellBackground(editor.colorsScheme)
+        else editor.colorsScheme.defaultBackground
     }
     super.updateUI()
   }