bug(windows): Blank help dialog appears when clicking a link.

### Describe the bug

The two help dialogs had the same topic, and if I close the second dialog and the first dialog becomes blank.

### Reproduce the bug

Steps to reproduce:

1. Install the Keyman-19.0.51.exe alpha build.
2. Start the Keyman app.
3. Open the configuration dialog.
4. Open the "Keyboard Configuration" window.
5. Install the "Greek Classical" keyboard by clicking the "Download Keyboard".
6. Open the "Greek Classical" help topic by clicking the "help" button.
7. Click the "Complete Typing Chart" link button.
8. Observed another help dialog.
Actual Results: Here, two help dialogs had the same topic and then closed the second help dialog.
Here, the help dialog becomes blank.
Please refer to the screenshot below

### Expected behavior

_No response_

### Related issues

_No response_

### Keyman apps

- [ ] Keyman for Android
- [ ] Keyman for iPhone and iPad
- [ ] Keyman for Linux
- [ ] Keyman for macOS
- [x] Keyman for Windows
- [ ] Keyman Developer
- [ ] KeymanWeb
- [ ] Other - give details at bottom of form

### Keyman version

19.0.51 alpha

### Operating system

Windows 10

### Device

Windows Desktop

### Target application

_No response_

### Browser

_No response_

### Keyboard name

Greek Classical

### Keyboard version

1.3

### Language name

Greek, Ancient(grc-Grek-GR)

### Additional context

_No response_