fix: Allow copy of excalidraw elements only when inside excalidraw (#3206)

* fix: Allow copy event only inside canvas

* use pointerdown

* use document.getSelection

* remove poiterdown

* remove keyTest

* update changelog

src/components/App.tsx

@@ -1028,6 +1028,13 @@ class App extends React.Component<ExcalidrawProps, AppState> {
   });
 
   private onCopy = withBatchedUpdates((event: ClipboardEvent) => {
+    const activeSelection = document.getSelection();
+    if (
+      activeSelection?.anchorNode &&
+      !this.excalidrawContainerRef.current!.contains(activeSelection.anchorNode)
+    ) {
+      return;
+    }
     if (isWritableElement(event.target)) {
       return;
     }