Problem description: There are two widgets on the dashboard, placed one above the other. The upper widget has a timeline displayed (for example "Problems" widget with option "Show timeline" set) and the widget below has its header hidden ("Show header" option unset). When hovering over the below widget, its header appears over the above widget, but under the timeline dots from the above widget.

Steps to reproduce:

1. Create a dashboard.
2. Add the 2 widgets to this dashboard:
   A - "Problems" widget with option "Show timeline" set.
   B - Any other widget with "Show header" option unset, right under the "Problems" widget
3. Save the dashboard.
4. Make sure You have enough problems for the timeline dots to reach the lower part of the "Problems" widget.
5. Hover over the lower widget in order for its header to appear.

Result: The lowest timeline dot from the "Problems" widget is displayed over the header of the lower widget, but all other content of the "Problems" widget are hidden under this header.

Expected: When the "hidden" header of the lower widget is displayed, it should be displayed over all content of the upper widget.

Example: