Add button to toggle sidebar in fullscreen mode
Summary:
Previously, there was no way to toggle the sidebar in
fullscreen view mode except for the keyboard shortcut F4. This patch
adds a button to toggle the sidebar from the fullscreen toolbar.
BUG: 414694
Test Plan:
Tested the button in fullscreen (view) mode. Button works
as expected, and preserves existing behavior of all other sidebar
toggle mechanisms as well.
Reviewers: VDG, Gwenview, ngraham
Subscribers: Gwenview
Tags: Gwenview
Differential Revision: https://phabricator.kde.org/D26230