换源窗口增加关闭按钮

app/src/main/java/io/legado/app/ui/book/changesource/ChangeBookSourceDialog.kt

@@ -241,6 +241,7 @@ class ChangeBookSourceDialog() : BaseDialogFragment(R.layout.dialog_book_change_
 
             R.id.menu_start_stop -> viewModel.startOrStopSearch()
             R.id.menu_source_manage -> startActivity<BookSourceActivity>()
+            R.id.menu_close -> dismissAllowingStateLoss()
             R.id.menu_refresh_list -> viewModel.startRefreshList()
             else -> if (item?.groupId == R.id.source_group && !item.isChecked) {
                 item.isChecked = true