Jan Paul Batrina authored Jul 12, 2021 and Christoph Cullmann committed Jul 13, 2021

bccc7d35 hides plugin views when their
sidebar is collapsed which made the sidebar unresizable.

This commit adds a placeholder (an empty QLabel) which is shown
when the sidebar is collapsed so that it will still be resizable.
The plugin views are properly shown again after the sidebar is
manually expanded using the mouse.