The cancel button in asset reimport dialog does not work when switching platforms. To reproduce:
- Open any project that takes non-trivial time to import (ex. TheChase)
- Switch platform between any mobile platform and standalone, or vice versa
- Observe all the assets being re-imported, with progress dialog with cancel button.
- Press the cancel button

Expected behavior:
Assert reimport and build process is cancelled as expected.

Observed behavior:
The import progress dialog is closed and replaced with another import dialog that does no longer have the cancel button, and the importing process continues until complete.