Newly dropped widget becomes hidden from the widget listing

[TanyaM]

Description:
If we add a new widget to the left side of the dashboard, that particular widget gets covered by the widget listing.
This should be fixed either by collapsing the widget listing when a new widget is added or by fitting the dashboard container to the space apart from the widget listing.

Affected Product Version:
4.0.28-SNAPSHOT

Steps to reproduce:

1. Create a dashboard and click on widget listing
2. Drag and drop a widget into the dashboard

Widget listing remains expanded and newly added widget is hidden by the listing pane.