refactor: 变量声明改成string

typescript/base/pane.ts

@@ -8,5 +8,5 @@ export interface _Pane extends _Widget {
 }
 
 export interface _PaneStatic {
-    EVENT_LOADED: "EVENT_LOADED";
-}
+    EVENT_LOADED: string;
+}

typescript/base/single/button/button.basic.ts

@@ -33,5 +33,5 @@ export interface _BasicButton extends _Single {
 }
 
 export interface _BasicButtonStatic {
-    EVENT_CHANGE: "BasicButton.EVENT_CHANGE";
+    EVENT_CHANGE: string;
 }