Preview window in the Duration bar graph is not expanding

**Describe the bug**
I can't expand preview window when I point my mouse to the Duration bar graph which shows the preview list of the test cases with the certain duration.

**To Reproduce**
Steps to reproduce the behavior:
1. Go to your demo https://demo.qameta.io/allure/#graph
2. Click on Graphs
3. Scroll down to the Duration bar graph
4. Choose the most level bar graph (it has 15 test cases) and point mouse on it. You will see the preview list. In the end of the list will be "... and 5 more" when I'm trying to expand that list(trying to point cursor into that window area), preview window disappears. As a result, I can't know any info about that hidden 5 test cases that were not included into the preview.

**Expected behavior**
I'm expecting to see full list of the test cases of the certain duration. Preview window is not expanding.

**Screenshots**

**Additional context**
Tested on my installed version of the Allure on Linux, same behavior. So just used your demo to describe the bug.

Also all other graphs like "Severity" have the same problem, if there are many tests!

Reproduce the issue from the demo URL at the Graphs page, using the Duration bar graph and a bar with many test cases. Inspect the preview behavior while moving the cursor toward the hidden entries; done means the preview stays open and exposes the full list, including cases beyond “... and 5 more.”

Written by the indexing model from the issue text.