fix(ComboBox): change background color if ComboBox instance is disabled

ui/modules/Common/Form/ComboBox.qml

@@ -26,7 +26,10 @@ ComboBox {
       width: ComboBoxStyle.background.border.width
     }
 
-    color: ComboBoxStyle.background.color
+    color: comboBox.enabled
+      ? ComboBoxStyle.background.color.normal
+      : ComboBoxStyle.background.color.readOnly
+
     radius: ComboBoxStyle.background.radius
 
     implicitHeight: ComboBoxStyle.background.height

ui/modules/Common/Styles/Form/ComboBoxStyle.qml

@@ -8,7 +8,6 @@ import Units 1.0
 
 QtObject {
   property QtObject background: QtObject {
-    property color color: Colors.k
     property int height: 36
     property int iconSize: 10
     property int radius: 4
@@ -18,6 +17,11 @@ QtObject {
       property color color: Colors.c
       property int width: 1
     }
+
+    property QtObject color: QtObject {
+      property color normal: Colors.k
+      property color readOnly: Colors.e
+    }
   }
 
   property QtObject contentItem: QtObject {