take color setting out of set model

GUI/Model/Type/ModelForSet.h

@@ -15,8 +15,8 @@
 #ifndef BORNAGAIN_GUI_MODEL_TYPE_MODELFORSET_H
 #define BORNAGAIN_GUI_MODEL_TYPE_MODELFORSET_H
 
+#include "GUI/Model/Type/PredefinedColors.h"
 #include <QAbstractListModel>
-#include <QWidget>
 
 template <class T> class SetWithModel;
 
@@ -45,8 +45,7 @@ public:
         case Qt::ToolTipRole:
             return t->description();
         case Qt::BackgroundRole:
-            return row == m_set->currentIndex() ? QWidget().palette().color(QPalette::Dark)
-                                                : QWidget().palette().color(QPalette::Button);
+            return GUI::Colors::listBackground(row == m_set->currentIndex());
         default:
             return {};
         }

GUI/Model/Type/PredefinedColors.cpp

@@ -13,6 +13,7 @@
 //  ************************************************************************************************
 
 #include "GUI/Model/Type/PredefinedColors.h"
+#include <QWidget>
 
 const QVector<QColor>& GUI::Colors::layerDefaults()
 {
@@ -22,3 +23,10 @@ const QVector<QColor>& GUI::Colors::layerDefaults()
 
     return colors;
 }
+
+const QColor& GUI::Colors::listBackground(bool isCurrent)
+{
+    static QVector<QColor> values = {QWidget().palette().color(QPalette::Button),
+                                     QWidget().palette().color(QPalette::Dark)};
+    return values.at(isCurrent);
+}

GUI/Model/Type/PredefinedColors.h

@@ -23,6 +23,8 @@ namespace GUI::Colors {
 
 const QVector<QColor>& layerDefaults();
 
+const QColor& listBackground(bool isCurrent);
+
 } // namespace GUI::Colors
 
 #endif // BORNAGAIN_GUI_MODEL_TYPE_PREDEFINEDCOLORS_H