Please give a brief summary of your issue:
When the screen is <640px, ‘contextMenuPopup’ cannot be used.
Please describe your issue and provide steps to reproduce it:
In the PDFTron source code, when the screen width is less than 640 px, right click on the screen does not pop up.
Apart from modifying the source code, there are other ways to use ‘contextMenuPopup’, when the screen is less than 640px.