fix null error when in full screen window

example/lib/main.dart

@@ -97,6 +97,25 @@ class _ExampleMihPackageState extends State<ExampleMihPackage> {
                 fontWeight: FontWeight.bold,
               ),
             ),
+            Icon(MihIcons.link),
+            MihButton(
+              width: 300,
+              onPressed: () {
+                showDialog(
+                  context: context,
+                  builder: (context) => MihPackageWindow(
+                    fullscreen: true,
+                    windowTitle: "Full Screen Test",
+                    onWindowTapClose: () {
+                      Navigator.pop(context);
+                    },
+                    windowBody: Placeholder(),
+                  ),
+                );
+              },
+              buttonColor: MihColors.green(),
+              child: Text("Press"),
+            ),
           ],
         ),
       ),

example/pubspec.lock

@@ -209,7 +209,7 @@ packages:
       path: ".."
       relative: true
     source: path
-    version: "0.0.5"
+    version: "0.0.6"
   path:
     dependency: transitive
     description: