1918883 - In extensions, drag & drop events are not emitted when entering another window after the first time

Status: RESOLVED DUPLICATE of bug 1918907

(Core :: DOM: Copy & Paste and Drag & Drop, defect)

Description

[bobo1239]

User Agent: Mozilla/5.0 (X11; Linux x86_64; rv:132.0) Gecko/20100101 Firefox/132.0

Steps to reproduce:

Steps to reproduce:

• Install the Sidebery extension (https://addons.mozilla.org/en-US/firefox/addon/sidebery/)
• Create a 2nd window and open the Sidebery sidebar on both windows.
• Drag a tab from the one window's sidebar to the other window's sidebar but don't drop it. Move the cursor outside the window and re-enter again.

Actual results:

When entering the 2nd window for the first time the extension works correctly and shows an indicator to drop the tab. But after re-entering the window the indicator is not shown again since the extension doesn't receive a onDragEnter event (and possibly others.)

Expected results:

The behavior after re-entering the window should be the same as the first time.

Comment 1

[bobo1239]

Attachment: good (9ac7f1f672d5).mkv

video of correct behavior (autoland push before Bug 1893119)

Comment 2

[bobo1239]

Attachment: bad (current nightly).mkv

video of incorrect behavior (current nightly)

Comment 3

[bobo1239]

(while the bad video is using the current nightly I did bisect the issue to https://hg.mozilla.org/integration/autoland/pushloghtml?changeset=01bfc9faa69043308206f123a4f171b426aa2758)

Comment 4

[bobo1239]

Small clarification: It is sufficient to drag between the Sidebery sidebar and the rendered webpage to observe this bug. (so don't need to exit the 2nd window)

This can be seen by opening e.g. https://google.com in the 2nd window. Then drag some text from the 1st window over the search field and then to the Sidebery sidebar. Both times the drop indicator is shown. But then continuing the drag back to the search field and back to the sidebar shows no indicators anymore.

Actually this can even be seen while just staying in the first window when dragging text from a webpage. The indicator is not shown anymore after re-entering the sidebar. But here it keeps working correctly on the webpage/content which originated the drag n' drop action.

Comment 5

[David Parks [:handyman]]

Thanks for the report -- the instructions are easy to follow and the issue is easy to see. I'm seeing it on Windows 11 but I assume it is cross-platform. It looks like it's fixed by the patch in bug 1918907.