Attach (recommended) or Link to PDF file here:
[test planning.pdf](https://github.com/mozilla/pdf.js/files/7305078/test.planning.pdf)

Configuration:
- Web browser and its version: Firefox 93
- Operating system and its version: Windows 10 21H2
- PDF.js version: The integrated version
- Is a browser extension: no

Steps to reproduce the problem:
1. In the example, all shape and the "Line" cell of the first cell have a comment
2. Mouse over a "Line" cell or a shape, nothing appear except on mouse over their border
3. It is too difficult to use
4. There is also a vertical orientation issue reported in bug #7631

What is the expected behavior? (add screenshot)
Comments are shown on mouse hover or mouse click inside a cell or a shape

What went wrong? (add screenshot)
Comments are not shown when mouse hover or clicking inside a cell or a shape, only on their border

![image](https://user-images.githubusercontent.com/7791600/136419088-e083e2a3-d376-4d8c-9e0b-ce9dd5b83923.png)



}
          
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              commitKey,
              selStart: event.target.selectionStart,
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                willCommit: true,
                commitKey: 1,