While uploading a file using filepicker click on the X button at the top right corner.
Confirmation popup is displayed, saying:
You are currently uploading. If you choose "OK", the window will close and your upload will not finish. Do you want to stop uploading and close the window?
If you press cancel, the same popup is displayed once again.
I can't reproduce it straight away. If you still have this issue please contact our support at support@filestack.com They'll help, or will be able to track down the bug so we (programmers) can fix it.
While uploading a file using filepicker click on the X button at the top right corner. Confirmation popup is displayed, saying:
If you press cancel, the same popup is displayed once again.