When theme color change we set the stylesheet.

src/Gui/PreferencePages/DlgSettingsTheme.cpp

@@ -47,6 +47,9 @@ DlgSettingsTheme::DlgSettingsTheme(QWidget* parent)
     ui->setupUi(this);
 
     connect(ui->styleSheetsCombobox, qOverload<int>(&QComboBox::activated), this, &DlgSettingsTheme::onStyleSheetChanged);
+    connect(ui->ThemeAccentColor1, &Gui::PrefColorButton::changed, this, &DlgSettingsTheme::onColorChanged);
+    connect(ui->ThemeAccentColor2, &Gui::PrefColorButton::changed, this, &DlgSettingsTheme::onColorChanged);
+    connect(ui->ThemeAccentColor3, &Gui::PrefColorButton::changed, this, &DlgSettingsTheme::onColorChanged);
 }
 
 /**
@@ -147,6 +150,10 @@ void DlgSettingsTheme::onStyleSheetChanged(int index) {
     styleSheetChanged = true;
 }
 
+void DlgSettingsTheme::onColorChanged() {
+    styleSheetChanged = true;
+}
+
 /**
  * Sets the strings of the subwidgets using the current language.
  */

src/Gui/PreferencePages/DlgSettingsTheme.h

@@ -54,6 +54,7 @@ protected:
 
 protected Q_SLOTS:
     void onStyleSheetChanged(int index);
+    void onColorChanged();
 
 private:
   std::unique_ptr<Ui_DlgSettingsTheme> ui;