Affected versions]
Release 76.0 (64-bit)
Beta 77.0b8 (64-bit)
Firefox Nightly 78.0a1 (2020-05-21) (64-bit)

[Affected platforms]
( macOS 10.14 (Mojave))

[Steps to reproduce]

1- Launch the Firefox Browser and visit https://en.wikipedia.org/wiki/Game_of_Thrones or https://www.w3schools.com/html/html_tables.asp
2- Open https://docs.google.com/spreadsheets
3- Select any desired amount of rows from the table in step 1 and copy with cmd c
4- Paste it in the online editor from step 2 with cmd v
5- Table is pasted successfully
6- Now click on menu edit/paste special/all except borders

[Expected result]
Table should be pasted accordingly

[Actual result]
Selection pasted is not correct.

If repeating steps in chrome, the table is correctly pasted, as shown in the attachment.

Works on Chrome.

Notice that in Beta 78.0b4 (64-bit) for macOS 10.5 no option from paste special is working, not just the "all except borders" option.

It seems Google spreadsheets uses its own clipboard for "paste special". Note that clicking the "paste" button from the menu will ask the user to paste via pressing Cmd/Ctrl+v.

I guess "paste special" has to use the async Clipboard API, which Firefox doesn't support fully yet.

Copying from inside Google spreadsheets and pasting via "paste special" to Google spreadsheets works.

Happens on Ubuntu too.

(In reply to Mirko Brodesser (:mbrodesser) from comment #4)

It seems Google spreadsheets uses its own clipboard for "paste special". Note that clicking the "paste" button from the menu will ask the user to paste via pressing Cmd/Ctrl+v.

I guess "paste special" has to use the async Clipboard API, which Firefox doesn't support fully yet.

Adding bug dependency for this.

Copying from inside Google spreadsheets and pasting via "paste special" to Google spreadsheets works.

Happens on Ubuntu too.

Setting this as WebCompat Priority P2 for now. This is somewhat annoying and Google Sheets is important, but it's probably not a P1 for us, since Google Sheets is usable and there is a workaround available.

Dennis: FYI, implementing and exposing the async clipboard API, which should fix or allow Google fixing this issue, is WIP (bug 1744524 and related ones).

(In reply to Mirko Brodesser (:mbrodesser) from comment #4)

Copying from inside Google spreadsheets and pasting via "paste special" to Google spreadsheets works.

Please note that this doesn't work even if copying from google spreadsheets to other google spreadsheets. For some reason this has not been fixed by bug 1744524.
For more details, please check the latest attachment.

(In reply to Cristian Baica [:cbaica], Release Desktop QA from comment #9)

Created attachment 9283634 [details]
paste special in google docs

(In reply to Mirko Brodesser (:mbrodesser) from comment #4)

Copying from inside Google spreadsheets and pasting via "paste special" to Google spreadsheets works.

Please note that this doesn't work even if copying from google spreadsheets to other google spreadsheets. For some reason this has not been fixed by bug 1744524.
For more details, please check the latest attachment.

Fixing bug 1744524 is prerequisite for fixing this bug. However, it's not sufficient. First, bug 1770358 will have to be fixed and afterwards Google Spreadsheets might need adaptation too.