BBE 3.6.0 video export double-dialog

[meoso]

• When exporting video, the expected save-as dialog appears. Video export processes, but file is not populated during this time, then upon export-completion, a second dialog appears and the file successfully saves from this second dialog.
• Unknown if this is limited to Linux or exists in all OS's.
• Ran this on Ubuntu 20.04
• Both BBE v20210105.1590 & BBE v20201226.1471 fail.
• v20201208.1320 works!
• reinstall nor reboot fixes (just in case)
• Linux 5.4.0-59-generic #65-Ubuntu SMP Thu Dec 10 12:01:51 UTC 2020 x86_64 x86_64 x86_64 GNU/Linux
• ScreenRecording of issue https://youtu.be/l_brn13_F4o

thank you

[mikeller]

Tested with Ubuntu 20.04, the double dialog reproduces.

[McGiverGim]

I've made a PR as temporary fix for that. I will let this open because the underline bug remains, to see if we can fix it in a future maintaining the FileWriter support.

[meoso]

honestly, the best solution for me was revert NW.js to 0.48.4 which was the last version that worked as expected.

[haslinghuis]

@meoso Yes we have a lot of work to do. Chrome API's are deprecated and we need to adapt. See betaflight/betaflight-configurator#2636

I guess we needed up to date NW.js versions for not crashing on M1

[McGiverGim]

This was totally fixed in #553 so I close this.