修改细节，增加图标和splash image，最后需要用破解版打包

Assets/Resources/UI/Control/PFUIDropdown.prefab

@@ -70,9 +70,9 @@ RectTransform:
   m_LocalEulerAnglesHint: {x: 0, y: 0, z: 0}
   m_AnchorMin: {x: 1, y: 0.5}
   m_AnchorMax: {x: 1, y: 0.5}
-  m_AnchoredPosition: {x: -15, y: 0}
-  m_SizeDelta: {x: 20, y: 20}
-  m_Pivot: {x: 0.5, y: 0.5}
+  m_AnchoredPosition: {x: -8, y: 0}
+  m_SizeDelta: {x: 16, y: 15}
+  m_Pivot: {x: 1, y: 0.5}
 --- !u!222 &5654717326227647255
 CanvasRenderer:
   m_ObjectHideFlags: 0
@@ -100,7 +100,7 @@ MonoBehaviour:
   m_OnCullStateChanged:
     m_PersistentCalls:
       m_Calls: []
-  m_Sprite: {fileID: 10915, guid: 0000000000000000f000000000000000, type: 0}
+  m_Sprite: {fileID: 21300000, guid: 5e0fe4d52e7b9f843971f6d603c6985c, type: 3}
   m_Type: 0
   m_PreserveAspect: 0
   m_FillCenter: 1