Ability to cache currency selection (#5)

lib/views/DropDownBox.dart

@@ -1,14 +1,15 @@
 import 'package:dropdown_search/dropdown_search.dart';
-import 'package:flutter/cupertino.dart';
 import 'package:flutter/material.dart';
 
 import '../Utils/Constants.dart';
 
 class DropDownBox extends StatelessWidget {
   final List<String> _selection;
+  final String _hintText;
   final Function(String?) _onChanged;
 
-  const DropDownBox(this._selection, this._onChanged, {super.key});
+  const DropDownBox(this._selection, this._hintText, this._onChanged,
+      {super.key});
 
   @override
   Widget build(BuildContext context) {
@@ -18,20 +19,21 @@ class DropDownBox extends StatelessWidget {
       shape: const RoundedRectangleBorder(
           borderRadius: BorderRadius.all(Radius.circular(22))),
       child: DropdownSearch<String>(
-        popupProps: const PopupProps.dialog(showSearchBox: true),
+        popupProps: const PopupProps.dialog(
+            showSearchBox: true,
+            dialogProps: DialogProps(backgroundColor: colourThree)),
         items: _selection,
-        dropdownDecoratorProps: const DropDownDecoratorProps(
+        dropdownDecoratorProps: DropDownDecoratorProps(
           dropdownSearchDecoration: InputDecoration(
-            contentPadding: EdgeInsets.all(14),
+            contentPadding: const EdgeInsets.all(14),
             border: InputBorder.none,
             filled: true,
             fillColor: Colors.transparent,
-            hintText: "Select a currency",
+            hintText: _hintText,
           ),
         ),
         onChanged: _onChanged,
       ),
     );
   }
-
-}
+}