fix dock spawn close

Author: jogibear9988

lib/es5/dock-spawn-ts.js

@@ -1,6 +1,6 @@
 {
   "name": "dock-spawn-ts",
-  "version": "3.10.0",
+  "version": "3.11.0",
   "description": "DockSpawn Typescript Version",
   "license": "MIT",
   "author": "[email protected]",

lib/js/PanelContainer.js

@@ -383,7 +383,7 @@ export class PanelContainer implements IDockContainerWithSize {
         this.isDialog = true;
         this.undockInitiator.enabled = false;
         this.elementContentWrapper.style.display = "block";
-        this.elementContentContainer.style.display = 'none';
+        this.elementContentContainer.style.visibility = 'hidden';
         this.elementPanel.style.position = "";
         this.dockManager.requestClose(this);
     }