Editing a .c file fails when // comment is edited

### Apache NetBeans version

Apache NetBeans 24

### What happened

When editing a .c file, if I move my cursor to a // commented section of code, I stop seeing the text I'm typing. I the editor thinks it's doing things, as the file name goes bold indicating unsaved changes but the text I typed does not appear. The cursor still moves via arrow keys or mouse clicks, just no text appearing when typing.

Seems to be intermittent, several close/open of NetBeans and the problem was there, several it wasn't. Unable to determine a pattern.

### Language / Project Type / NetBeans Component

C

### How to reproduce

Open existing .c file, type // and further text doesn't show.

or

Open existing .c file, click after // and further text doesn't show.

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

Apache NetBeans 19

### Operating System

macOS 15.2 on Apple M1 Pro

### JDK

Java: 19.0.1; Java HotSpot(TM) 64-Bit Server VM 19.0.1+10-21

### Apache NetBeans packaging

Apache NetBeans provided installer

### Anything else

Also happened on 3rd party .pkg installed app.

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

No

No source file or test is named. Reproduce the issue in Apache NetBeans 24 by editing a .c file and typing after //, then compare behavior across repeated editor sessions. Done means text entered in a // comment remains visible while the cursor is moved and the file is edited.

Written by the indexing model from the issue text.