Cloned tab with "Design view" capability has no content inside

### Apache NetBeans version

Apache NetBeans 24

### What happened

When you clone the tab which have the "Design View" capability available, its content is empty. It's necessary to perform some kind of "refresh" operation to display its content (for example to switch between Design and Source View).


### Language / Project Type / NetBeans Component

Java Project with Ant

### How to reproduce

See the issue description.

### Did this work correctly in an earlier version?

No / Don't know

### Operating System

Ubuntu 22.04
Windows 10
Windows 11

### JDK

OpenJDK 64-Bit JRE 21.0.5+11-Ubuntu-1ubuntu122.04
Eclipse Temurin OpenJDK 23.0.1+11

### Apache NetBeans packaging

Apache NetBeans provided installer

### Anything else

_No response_

### Are you willing to submit a pull request?

No

Start by reproducing the issue in Apache NetBeans 24: clone a tab with Design View available and verify that its content is initially empty on the listed systems and JDKs. Compare the cloned tab with the original and use the Design/Source switch as a diagnostic; done means the cloned tab displays its content immediately without a refresh.

Written by the indexing model from the issue text.