After a selection viewport movement does not work on mobile

[mondolirondo]

I have observed it in my own application as well as in the online demo of the plugin. Tested on a few mobile browsers: chome, opera, samsung internet. It seems to work on Firefox.
Steps to reproduce:

1. Open demo page on a mobile browser (chome, opera, samsung internet): https://picturae.github.io/openseadragonselection/
2. Drag viewport with one finger to move, movement is smooth
3. Enable selection
4. Drag and create a selection. Close the dialog with information.
5. Disable selection
6. Drag viewport with one finger to move, movement is no longer working properly