Notifications are overlapping more than their visible parts

Note: affect version to be refined

Reproduction steps

1. resize your browser window to about 800x600px
2. open the object editor of any page
3. add an object
4. click on cancel before the success notification fades out

expected

When the notification does not overlap the cancel button, clicking on cancel performs the action

actual

Clicking on cancel dismiss the notification instead of performing the cancel action.
Meaning that even though the visual part of the notification does not overlap with the cancel button, some transparent part of it does.

Note: I made a recording of the issue, this is probably not easy to grasp but I had to click two to actually cancel.

PS: this can create flakyness under some condition in functional tests.