UserAgent: Mozilla/5.0 (Windows NT 10.0; Win64; x64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/61.0.3163.100 Safari/537.36

Steps to reproduce the problem:
1. drag a draggable into a dropzone
2. wait for the cursor to change to move/copy icon
3. drag it out fast and release mouse immediately (before the icon changes back to none/forbidden icon)
4. inspect the dragend-event's dropEffect
5. Try again, but this time wait for the icon to change

What is the expected behavior?
The dropEffect should be "none" since the drop was not allowed outside the dropzone.

What went wrong?
According to the spec's processing model the dropEffect should be calculated before emitting the drop and dragend events. The drop event in the test case is NOT emitted, so the basic calculation of the validity of the drop must be correct. Although the dropEffect is not set correctly. Test Step 5 shows, that the error occures only when the drop/mouse release happens during step 3.2 (dragleave) or 3.3 in the processing model. This translates to the dragleave handler or possibly the dragover directly after it, since the next step is the setting of the icon. If a blocking wait is added to the dragleave handler the issue can be reproduced every time.

Did this work before? N/A 

Does this work in other browsers? No
 Microsoft Edge: NOT REPRODUCED, shows expected behaviour
Mozilla Firefox: REPRODUCED, no reported bug found

Chrome version: 61.0.3163.100  Channel: stable
OS Version: 10.0
Flash Version: 

The attached test case can also be run online here: https://codepen.io/anon/pen/NazzNK?editors=1111

It contains a wait in the dragleave handler of the dropzone to make reproduction easier, for the pure test case remove the wait.

This might be connected to (although only symptomatically) https://bugs.chromium.org/p/chromium/issues/detail?id=715778
 

Deleted: codepen_NazzNK.zip 2.2 KB

codepen_NazzNK.zip 2.2 KB Download